### Specifically Designed Constructe d Wetlands: A Novel Treatment Approach for Scrubber Wastewater

Scientific Final Report September 1, 2004—September 1, 2005

Prepared by:

John H. Rodgers, Jr., Ph.D., Professor, Clemson University James W. Castle, Ph.D., Assoc. Professor, Clemson University Chris Arrington, Graduate Resear ch Assistant, Clemson University

Derek Eggert, Graduate Research Assistant, Clemson University Meg Iannacone, Graduate Research Assistant, Clemson University

September 2005

United States Department of Energy

Award # DE-FG26-04NT42178

Clemson University

300 Brackett Hall Clemson, SC 29634- 1- Disclaimer

“This report was prepared as an account of work sponsored by an agency of the United States

Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or im plied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or re presents that its use would not infringe privately owned rights. Reference herein to any specific commercial pr oduct, process, or service by trade name, trademark, manufacturer, or othe rwise does not necessarily consti tute or imply its endorsement, recommendation, or favoring by th e United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof.”- 2- 

### Foreword

This scientific progress report is organized by the three research objectives or tasks:

Task 1: To measure performance of a pilot-scale cons tructed wetland treatment system in terms of decreases in targeted constituents (Hg, Se and As) in FGD wastewater.

Task 2: To determine how the observed performance is achieved (both reactions and rates) through sequential extractions of these elements from sediments.

Task 3: To measure performance in terms of decreased bioa vailability of these elem ents (i.e. toxicity of

sediments in constructed wetlands and toxicity of outflow waters from the treatment system).

Within the report, each section is divided and classified as TASK 1, 2, and 3. Discussions and conclusions are included in each section, along with an overall conclusion from data collected during the full year of funding.- 3- 

### Abstract

A pilot-scale wetland treatment system was speci fically designed and constructed at Clemson University to evaluate removal of mercury, selenium, and other constituents from flue gas desulfurization (FGD) wastewater. Specific object ives of this research were: (1) to measure performance of a pilot-scale c onstructed wetland treatment system in terms of decreases in targeted constituents (Hg, Se and As) in the F GD wastewater from inflow to outflow; (2) to determine how the observed performance is achie ved (both reactions and rates); and (3) to measure performance in terms of decreased bioava ilability of these elemen ts (i.e. toxicity of

sediments in constructed wetlands and toxicity of outflow waters from the treatment system).

Performance of the pilot-scale constructed we tland treatment systems was assessed using two criteria: anticipated NPDES permit levels and toxi city evaluations using two sentinel toxicitytesting organisms ( Ceriodaphnia dubia and Pimephales promelas ). These systems performed efficiently with varied inflow simulations of FGD wastewaters re moving As, Hg, and Se concentrations below NPDES permit levels a nd reducing the toxicity of simulated FGD wastewater after treatment with the constructed wetland treatment systems. Sequential extraction procedures indicated that these elements (As, Hg, and Se) were bound to residual phases within sediments of these systems, which should limit their bioavailability to aquatic biota.

Sediments collected from constructed wetland treat ment systems were tested to observe toxicity

to Hyalella azteca or Chironomus tetans . Complete survival (100%) was observed for H. azteca in all cells of the constructed wetland treatment system and C. tentans had an average of 91%

survival over the three treatment cells containing sediments. Survival and growth of H. azteca

and C. tentans did not differ significantly between se diments from the constructed wetland treatment system and controls. Since the sediments of the constructed wetland treatment system are repositories for As, Hg, and Se and the bioa vailability of these elements decreased after deposition, the pilot-scale constr ucted wetland treatment system contributed significantly to mitigation of risks to aquatic life from these elements.- 4- 

### Executive Summary

A pilot-scale wetland treatment system was speci fically designed and constructed at Clemson University to evaluate removal of mercury, selenium, and other constituents from flue gas desulfurization (FGD) wastewater. Specific object ives of this research were: (1) to measure performance of the pilot-scale constructed wetland treatment syst em in terms of decreases in targeted constituents (Hg, Se and As) in the F GD wastewater; (2) to determine how the observed performance is achieved (both re actions and rates); and (3) to m easure performance in terms of decreased bioavailability of these elements (i.e. toxicity of sediments in constructed wetlands and toxicity of outflow waters from the treatment system). This Scientific Final Progress Report provides a description of the c onfiguration and current design characteristics of the pilot constructed wetland treatment system and pe rformance results. In itial evaluations of performance contained in this progress report involved FGD wa stewaters formulated based upon analyses of several actual FGD waters.

Performance of the pilot constructed wetland treatment systems at this final stage indicates that the system is decreasing aqueous concentrations of the targeted wastewater constituents (As, Hg, and Se) for the majority of the wastewaters. The removal rates of mercury were consistently greater than 90% for three of simulated FGD wa stewaters tested and ranged from 64% to 97% for all FGD wastewaters except fo r the high ionic strength FGD wa stewater (week 7), in which the concentration of mercury was already be low the predicted NPDES permit level of 0.001 mg/L. Selenium removal rates were relatively st able throughout this study with a range of 84 to 90% removal by the pilot-scale constructed we tland treatment systems. Arsenic removal, however, varied throughout the st udy with higher removal rates occurring during the high ionic strength FGD wastewaters (~70%). Removal rates of arsenic in these simulated FGD wastewaters are of lesser importance than Hg or Se, since the actual FGD wastewaters that we have analyzed to date had lower concentratio ns of arsenic than the specified NPDES limits. Sequential extraction procedures we re used to quantitatively measure the immobilization of these elements of concern in the sedimentary compone nt of these systems. Data gathered by this procedure indicate that most of As, Hg, and Se is bound to resi due phases within the sediment,

and the dissolution or re-solubil ity of these elements is unlik ely to occur under environmental conditions within this treatment system ( not thermodynamically favored). In toxicity experiments, we observed a significant increa se in survival, grow th, and reproduction for organisms exposed to samples of the final outfl ow versus inflow simulated FGD wastewater. Chloride concentrations are an important factor in this treatment process and satisfactory chloride levels (~4000mg/L) were achieved in these experiments by dilution with moderately

hard water.

Components of the system were manipulated to enhance removal of these targeted constituents and the contributions of these changes to transf ers and transformations of As, Se, and Hg were assessed. Toxicity evaluations were conducted to relate these system component changes to bioavailability of these elements to the sentinel species used in NPDES toxicity tests. Bulk sediment toxicity was evaluated using both H. azteca and C. tentans . Since the sediments of the constructed wetland treatment syst em are repositories for As, Hg, and Se and the bioavailability of these elements decreased after deposition, the pilot-scale constructed wetland treatment system contributed significantly to mitigation of risks to aquatic life from these elements.- 5- Table of Contents

ABSTRACT....................................................................................................................... ............ 3

EXECUTIVE SUMMARY..................................................................................4



### TASK ONE ...........................................................................................................................9-4 8

INTRODUCTION................................................................................................................... ..... 9

MATERIALS AND METHODS ............................................................................................... 10 System Configuration ........................................................................................................... ........ 10

Actual FGD Wastewater.......................................................................................................... ..... 11

Simulated FGD Wastewater ....................................................................................................... .. 11 Analytical Methods............................................................................................................. .......... 13

Evaluation of Wetland Plants................................................................................................... ..... 14

RESULTS ........................................................................................................................ ............. 14 Primary Targeted Constituents .................................................................................................. ... 14

Other Constituents of Interest ................................................................................................. ...... 17

DISCUSSION ..................................................................................................................... ......... 46

CONCLUSIONS .................................................................................................................... ..... 47

REFERENCES..................................................................................................................... ....... 48



### TASK TWO

...................................................................................................................... 49-55

INTRODUCTION................................................................................................................... .... 49

MATERIALS AND METHODS ............................................................................................... 48 Sequential Extraction Procedures..........................................................................49

RESULTS

............................................................................................................................... ..... 51

DISCUSSION ..................................................................................................................... ......... 54

CONCLUSIONS .................................................................................................................... ..... 54

REFERENCES..................................................................................................................... ....... 55



### TASK THREE

................................................................................................................... 56-69

INTRODUCTION................................................................................................................... .... 56

MATERIALS AND METHODS ............................................................................................... 57

Toxicity Experiments.........................................................................................57

RESULTS

............................................................................................................................... ..... 60

DISCUSSION ..................................................................................................................... ......... 69

CONCLUSIONS .................................................................................................................... ..... 70

OVERALL CONCLUSIONS..............................................................................71

REFERENCES..................................................................................................................... ....... 72- 6- List of Tables

Table 1. Acclimation FGD wastewater loaded into the pilot-scale constructed wetland treatment system (listed as weeks 1-4).

Table 2. Classification and targeted concentrations of el ements of interest in four simulated FGD wastewaters used throughout this phase one DOE study. Table 3. Targeted constituents and s ources for simulated FGD wastewater. Table 4. Analytical methods fo r parameters monitored weekly from the FGD pilot constructed wetland systems. Table 5. Simulated FGD wastewater physical a nd chemical properties analyzed in a pilot constructed wetland system. Table 6. Monthly hydrosoil ox idation-reduction (redox) potent ial in the FGD pilot-scale constructed wetland systems. Table 7. Summary of sequential extraction procedures for Hg (modified from Lechler et al. 1997).

Table 8

. Summary of sequential extraction method fo r Se (modified from Chao and Sanzolone 1989). Table 9. Summary of sequential extraction procedure for As (modified from Wenzel et al. 2001 and Schank 2003).

Table 10

. Summary of sediment characteristics.

Table 11. Elements and form used for amendments of simulated FGD wastewater.

Table 12. Analytical methods for parame ters monitored for FGD wastewater.

Table 13. Measurements of parameters from in flow to outflow of the constructed wetland

treatment systems.

Table 14. Sediment toxicity results in terms of survival and growth measurements of Hyalella

azteca for wetland treatments and controls.

Table 15. Sediment toxicity results in terms of survival and growth measurements of

Chironomus tentans for wetland treatments and controls.

List of Figures

Figure 1. Schematic of the pilo t constructed wetland system fo r evaluating treatment of FGD

wastewater. Figure 2. Pilot constructed wetland system at Clemson University for treating FGD wastewater. Figure 3. Total mercury in simulated FGD wastew ater treated by a pilot constructed wetland system during the acclimation period (Weeks 1 to 4). Figure 4. Average total mercury in simulated FGD wastewater treated by a pilot constructed wetland system for the high ionic stre ngth FGD wastewater (Weeks 9 and 10). Figure 5. Average total mercury in simulated FGD wastewater treated by a pilot constructed wetland system for the high-intermediate ionic strength FGD wastewater (Weeks 11 to 20). Figure 6. Total mercury in simulated FGD wast ewater treated by a pilo t constructed wetland system for the first week of low-in termediate ionic strengt h FGD wastewater (Week 23).- 7- Figure 7. Total mercury in simulated FGD wast ewater treated by a pilo t constructed wetland system for the second week of lo w-intermediate ionic strength FGD wastewater (Week 24). Figure 8

. Total selenium in simulated FGD wastewater treated by a pilot constructed wetland system during the acclimation period (Weeks 1 to 4). Figure 9. Average total selenium in simulated FGD wastewater treated by a pilot constructed wetland system for the high ionic st rength FGD wastewater (Weeks 9 and 10). Figure 10

. Average total selenium in simulated FGD wa stewater treated by a pilot constructed wetland system for the high-intermed iate ionic strength FGD wastewater (Weeks 11 to 20). Figure 11. Total selenium in simulated FGD wastewater treated by a pilot constructed wetland system for the first week of low-in termediate ionic strength FGD wastewater (Week 23). Figure 12. Total selenium in simulated FGD wast ewater treated by a pilo t constructed wetland system for the second week of lo w-intermediate ionic strength FGD wastewater (Week 24). Figure 13. Average total arsenic in simulated FGD wastewater tr eated by a pilot constructed wetland system for the high ioni c strength FGD wastewater (Weeks 9 and 10). Figure 14. Average total arsenic in simulated FGD wastewater treated by a pilot constructed wetland system for the high-intermediate ionic strength FGD wastewater (Weeks 11 to 20). Figure 15. Total arsenic in simulated FGD wast ewater treated by a p ilot constructed wetland system for the first week of low-intermed iate ionic strength FGD wastewater (Week 23). Figure 16. Total arsenic in simu lated FGD wastewater treated by a pilot constructed wetland system for the second week of low-intermediate ionic strength FGD wastewater (Week 24). Figure 17. Hydrosoil oxidation-re duction (redox) potentia l for Train A of the FGD pilot-scale constructed wetland system. Figure 18. Hydrosoil oxidation-re duction (redox) potentia l for Train B of the FGD pilot-scale constructed wetland system. Figure 19. Hydrosoil oxidation-re duction (redox) potentia l for Train C of the FGD pilot-scale constructed wetland system. Figure 20

. Sequential extraction of Hg (A), Se (B), and As (C) in sediment collected from the first, second, and fourth planted wetland cells. Figure 21. Response, in terms of survival, of C. dubia to the inflow and the outflow from the treatment system for Sample One simulated FGD wastewater (Trains A, B, and C combined). Concentrations of 0.39% post-treatment and 50% pre-treatment were not

tested Figure 22. Response, in terms of survival, of C. dubia to the inflow and the outflow from the treatment system for Sample Two simulated FGD wastewater (Trains A, B, and C combined). Concentrations of 0.39% pos t-treatment and 50% pre-treatment were not

tested. Figure 23. Response, in terms of survival, of P. promelas to the inflow and the outflow from the treatment system for Sample One simulated FGD wastewater (Trains A, B, and C- 8- combined). Concentrations of 0.39% post-treatment and 50% pre-treatment were not

tested. Figure 24. Response, in terms of survival, of P. promelas to the inflow and the outflow from the treatment system for Sample Two simulated FGD wastewater (Trains A, B, and C combined). Figure 25. Response, in terms of reproduction, of C. dubia to the inflow and the outflow from the treatment system for Sample One simulate d FGD wastewater (Trains A, B, and C combined). Concentrations of 0.39% post-tr eatment and 50% pre-treatment were not

tested. Figure 26. Response, in terms of reproduction, of C. dubia to the inflow and the outflow from the treatment system for Sample Two simulated FGD wastewater (Trains A, B, and C combined). Concentrations of 0.39% post-tr eatment and 50% pre-treatment were not

tested. Figure 27. Comparative responses, in terms of survival, of C. dubia and P. promelas to simulated FGD wastewater Sample One. Figure 28. Comparative responses, in terms of survival, of C. dubia and P. promelas to simulated FGD wastewater Sample Two. Concen trations of 0.39%, 0.78%, 1.56%, and 3.125%

for P. promelas and 37.5%, 50%, 62.5%, and 75% for C. dubia were not tested. Figure 29. Comparative responses, in terms of survival, of C. dubia to simulated FGD wastewater Samples One and Two. Figure 30. Comparative responses, in terms of survival, of P. promelas to simulated FGD wastewater samples one and two. C oncentrations of 0.39%, 0.78%, 1.56%, and 3.125% for Sample Two and 37.5%, 50%, 62.5%, and 75% for Sample One

were not tested.- 9- Scientific Final Report



### TASK 1

Introduction

The purpose of this document is to report pr ogress on this study conducted to evaluate the efficacy of specifically designed constructe d wetland systems for tr eatment of flue gas desulfurization (FGD) wastewater , reactions and rates (for Hg, Se, and As), and toxicity of discharged wastewater from these systems. In order to efficiently implement FGD units at fossil-fueled power plants, an effective and relia ble wastewater treatment system is needed. Large volumes of wastewater will be produced at each site from the FGD process, and that water must be treated to eliminate contaminants in order to achieve discharge limitations established

under the Clean Water Act and National Pollution Discharge Elimination System (NPDES) The treatment system must be reli able and performance must be continuously achieved throughout all seasons of the year. Elements such as chloride , mercury, selenium, and ar senic are generally of concern in these wastewaters. Generic para meters such as biochemical oxygen demand (BOD) and chemical oxygen demand (COD) may also be targeted constituents for treatment. The specific targeted constituents va ry spatially th roughout the U.S., therefor e discharge limits of these constituents were chosen to encompass the majority of regulatory NPDES limits.

Specifically designed constructed wetland treatment systems have b een used to treat each of these elements independently, and we have recent data indicating success based upon this concept or technology for actual FGD wastewat er. Wetlands possess unique reactions not occurring in other a quatic or terrestrial system s. Constructed wetlands ca n be poised or buffered to ensure that desired reactions (transfers and transformations) affecting the targeted wastewater constituents proceed at predicta ble rates over long periods. In or der to develop confidence in the ability of a constructed wetland treatment system to treat a specific FGD wastestream, a pilot study is needed. A pilot study will provide strong proof-of-concept data and convincing information to assist with regulatory permitti ng of the full-scale facility. Alternatives to treatment with a constructed wetland system are not attractive due to high capital costs and continuing high costs associated w ith operation and maintenance.

The goal of this project was to design construc ted wetland treatment systems to effectively and consistently treat FGD wastewater in pilot-sc ale constructed wetland treatment systems. This report describes the progress of this pilot study by reporting the performance of each system and evaluates treatment effectiveness during all seas ons. The pilot study involves a scaled model constructed wetland treatment system (i.e., wetla nd microcosms to decrease uncertainties and confirm design features for the proposed full-scal e constructed wetland treatment systems). This report identifies the project obje ctives, outlines methods of analys es, and provides results for the pilot study.



### Experimental Methods

Specific objectives of this pilot-scale research are: 1. Measure performance of a pilot-scale constructed wetland treatment system in terms of decreases in targeted constituen ts (Hg, Se and As) in the FGD wastewater. 2. Determine how the observed performance is achieved (both reactions and rates).- 10- 3. Measure performance in terms of decreased bioavailability of these elements (i.e. toxicity of sediments in constructed wetlands and toxicity of outflow waters from the treatment system).



### Materials and Methods

System Configuration

The pilot constructed wetland treatment system (Fig. 1 and 2) was configured at Clemson University in Clemson, SC. The system cons ists of a 6,800-L upstream equalization basin followed by three parallel treatment trains. Each trea tment train consists of four stages in series (from upstream to downstream), including two we tland cells planted w ith bulrush, a gravel manganese oxidation basin, and a fi nal wetland cell planted with cattails. Each treatment stage was comprised of a 378-L Rubbermaid  utility tank. Overlying water depth and hydrosoil depths were 30 cm each in the wetland cells. Total hydraulic retention time (HRT) was four days (24 hours per treatment stage). Wastewater was pumped to each treatment train from the equalization basin at a constant rate using FMI  (Fluid Metering, Inc.) piston pumps (one pump per treatment train). Flow through the treatment system trains was by gravity.

Figure 1. Schematic of the pilot constructed wetla nd system for evaluating treatment of FGD

wastewater. Pumps

Equalization Basin Flow

A B C

Wetland Cell 1

Wetland Cell 2 Manganese

Oxidation Basin Final Wetland Cell- 11- Actual FGD Wastewater

Actual FGD wastewaters were analyzed for the major elemental constituents of concern (Hg, As, Se) using ICP-MS and for other water quality parameters such as Cl, SO 4 2- , COD, BOD, NPOC TSS, and TDS using Standard Methods for the Exami nation of Water and Wastewater (APHA 1998). Simulated FGD wastewater was synthesized based on results from these analyses.

Simulated FGD Wastewater

The chemical composition of FGD wastewater is site-specific and a treatment system must be robust to treat varying concentr ations of toxic constituents. Therefore, four simulated FGD wastewaters were used, in order to understand the removal rates and extents of ea ch independent wastewater resulting from treatme nt with specifically designe d constructed wetlands. These

wastewaters included acclima tion, high, high-intermediate, lo w-intermediate, and low ionic strength simulated FGD wast ewater (see Table 1 and 2).

Acclimation of the pilot constructed wetland system to mercury, selenium, arsenic, and chloride was accomplished (Table 1). Following the trea tment acclimation period and finalization of a list of constituents targeted for removal, FGD wastewater was simulated and introduced to the pilot constructed wetland system. Several source materials were mixed with municipal water (5,000 L per week) in the upstream equalization ba sin to provide the targeted FGD wastewater constituents (Table 3).

Formulation of simulated FGD wast ewater initially included CaCl 2 as a source for chloride, and nitric acid was added to neutralize pH. Th e final formulation differed from the initial formulation in that calcium and magnesium chloride salts were used as chloride sources. In subsequent formulations of simulated FGD wa stewater fly ash was added and dibasic acid (DBA) replaced nitric acid. Formulations were consistent afte r that adjustment. Figure 2 . Pilot constructed wetland system at Clemson University for treating

FGD wastewater.- 12- For the first phase of this project, sampling was conducted for elemental analysis (Hg, As, and Se) of inflow and outflow wastewater. After four weeks of loading, the pilot constructed wetland systems were sampled weekly for all water quality parameters listed in Table 3. Water samples were collected in 1000-mL Nalgene  containers from the equaliz ation basin and outflow from each treatment stage. Ou tflow samples were collected on a ti me course commensurate with HRT (i.e., wetland cell 1 was sampled 24 h after sa mpling the equalization basin, wetland cell 2 was sampled 48 h after sampling the equalization ba sin, etc.). Aqueous samples of 10-ml were immediately preserved with concentrated trace me tal grade nitric acid to pH < 2 for metals analysis, while the other 990-ml wa s retained for the remaining anal yses and toxicity tests.

Table 1 . Acclimation FGD wastewater loaded into the pilot-scale constructed wetland treatment system (listed as weeks 1-4).

Constituent Week 1 Week 2 Week 3 Week 4 Mercury (Hg(NO 3 ) 2 ·H 2 O) 0.027 mg/L 0.054 mg/L 0.070 mg/L 0.136 mg/L

Selenium (Na 2 SeO 4 ) 1.0 mg/L 2.0 mg/L 3.7 mg/L 7.5 mg/L

Chloride (CaCl 2 ) 1,000 mg/L 2,000 mg/L 4,000 mg/L 6,000 mg/L

Table 2. Classification and targeted con centrations of elements of in terest in four simulated FGD wastewaters used throughout this phase one DOE study. FGD Wastewater Type Treatment

Period Arsenic Mercury Selenium

High Ionic Strength Weeks 5- 10 0.300 mg/L 0.02 mg/L 8.00 mg/L

High-Intermediate Ionic Strength Weeks 11-20 0.180 mg/L 0.002 mg/L 4.50 mg/L

Low-Intermediate Ionic Strength Weeks 23-24 0.070 mg/L 0.160 mg/L 1.80 mg/L

Low Ionic Strength Weeks 21- 22 0.0025 mg/L 0.001 mg/L 0.060 mg/L- 13- Table 3 . Targeted constituents and sour ces for simulated FGD wastewater.

Constituent Target Inflow Source Target Outflow

Concentration Concentration 1

Mercury (Hg) 0.02 mg/L Hg(NO 3 ) 2 ·H 2 O 0.001 mg/L

Selenium (Se) 7.4 mg/L Na 2 SeO 4 0.4 mg/L

Arsenic (As) 0.28 mg/L NaAsO 2 0.15mg/L

Chloride (Cl) 4000 mg/L CaCl 2 MgCl 2 ·6H 2 O

Sulfate (SO 4 -2 ) 3000 mg/L CaSO 4
Boron (B) 20 mg/L Na 2 B 4 O 5 ·8H 2 O

Chemical Oxygen 100 mg/L Dibasic Acid (DBA)

Demand

Total Suspended 1000 mg/L Fly ash

Solids

1 Target concentrations chosen fr om reviews of local NPDES permits.

Additional Analyses

Oxidation-reduction (redox) poten tial of wetland hydrosoil was monitored monthly by placing platinum-tipped electrodes in situ and measuring the electrochemi cal potential with an Accumet 
calomel reference electrode (Faulkner et al., 1989). Dissolved oxygen and pH of inflow and outflow wastewater were measured using YSI  and Orion ® field instruments, respectively. Additional constituents and pr operties (Table 1) including alkalinity, hardness, conductivity, chloride and sulfate concentrations, chem ical oxygen demand, biologi cal oxygen demand, nonpurgeable organic carbon, and total and suspen ded solids were determined according to Standard Methods for the Examinati on of Water and Wastewater (APHA 1998).

Table 4. Analytical methods for parameters monitored weekly from the FGD pilot constructed wetland system.

Parameter Method Method Detection Limit

Temperature Direct Instrument ation: YSI Model 52 0.5°C

pH Direct Instrumenta tion: Orion Model 420A 0.01

Conductivity Direct Instrument ation: YSI 30 0.1 μS/cm

Alkalinity Standard Methods: 232 0 B 2 mg/L as CaCO3

Hardness Standard Methods: 2340 C 2 mg/L as CaCO3

DO 1 Direct Instrumentation: YSI Model 52 0.1 mg/L- 14- COD 2 Closed reflux colorimetry (HACH - 3 mg/L modified from Standard Methods: 5220D)

NPOC 3 Shimadzu TOC-V CPH Total Organic 4 μg/L Carbon Analyzer

BOD 5 4 Standard Methods: 5210 B 0.1 mg/L

TSS 5 Standard Methods: 2540 D 0.1 mg/L

TDS 6 Standard Methods: 2540 C 0.1 mg/L

Selenium Inductively Coupled Plasma (ICP): EPA 200.7 0.0022 mg/L

Mercury Inductively Coupled Pl asma (ICP): EPA 200.7 0.0001 mg/L

Chloride HACH Colorimetric Method 8207 25 mg/L

Sulfate Standard Methods: 4500 E 1 mg/L

Arsenic ICP: EPA 200.7 0.0013 mg/L

Boron ICP: EPA 200.7 0.0009 mg/L

1 Dissolved Oxygen

2 Chemical Oxygen Demand

3 Non-purgable Organic Carbon

4 Five-day Biological Oxygen Demand

5 Total Suspended Solids

6 Total Dissolved Solids

Evaluation of Wetland Plants

In response to observed stress of wetland vegetation due to chlori de levels (target influent concentration 6,000 mg/L), the simulated FGD wastewater was decreased to a chloride concentration of 4,000 mg/L to ensure the health of aquatic vegetation.



### Results

Primary Targeted Constituents

Mercury

High Ionic Strength FGD Wastewater

During the fifth week of treatment, the total mercury in the equalization basin was 0.0460 mg/L and by the final outflow, the total mercury had declined to 0.0003mg/L. The removal of total mercury by the pilot constructed wetland system was 98%, with a 91% removal by the outflow

of the first wetland cell for this treatment. The following week (week 6), the system produced similar results, with removal of 64, 84, 94, and 93% at the outflows of th e sequential treatment cells. At week 7, the total me rcury measured in the equaliza tion basin was 0.0019mg/L. There was no removal of mercury in the first two cells , however, 35% decrease in mercury content was observed in the manganese oxidation basin and 0. 0007 mg/L at the final outflow, which achieved- 15- a 61% removal. At week 8, total mercury d ecreased from 0.0154 mg/L (average inflow concentration) to 0.0012 mg/L (average final outf low). The next sampling event began in which total mercury decreased from 0.0080 mg/L (inflo w average) to 0.0010 mg/L (outflow average) (Table 5). Performance between the three treat ment trains was similar, with total mercury removal averaging 91% (Fig. 3).

High-Intermediate Ionic Strength FGD Wastewater

Dilution of the simulated FGD wastewater began with the high-intermediate ionic strength FGD wastewater (weeks 11 through 20) to achieve a chloride level (~4,000mg/L) compatible to the vegetation. Total mercury during th is time decreased from an av erage (all treatment trains) of 0.0029 mg/L ( ± 0.0004) mg/L in the inflow to 0.0002 mg/L ( ± 0.00005) mg/L in the final outflow, or 94% removal (Fig. 5).

Low-Intermediate Ionic Strength FGD Wastewater

Analysis of mercury removal by the pilot constructed wetland sy stems for week 23 indicated an average influent mercury c oncentration of 0.1467 mg/L ( ± 0.0115) (Fig. 6). Final outflow concentrations at this sampling event for tr eatment trains A, B, and C were 0.0072 mg/L, 0.0010 mg/L, and 0.0069 mg/L, respectively, or an overall removal of 97%. The final week, week 24, influent mercury concentra tions averaged 0.17 mg/L ( ± 0.0058), while final outflow concentrations for trains A, B, an d C were 0.0069 mg/L, 0.0071 mg/L, and 0.0080 mg/L, respectively (96% removal) (Fig. 7).

Selenium

High Ionic Strength FGD Wastewater

Overall, performance of the pilot system trea ting undiluted simulated FGD wastewater (~6,000 mg/L chlorides) was approximately 85% removal of total selenium (Fig. 9). Total selenium

concentrations in the equalization basin averaged 7.7 mg/L, and ranged from 7.1 to 8.5 mg/L for weeks 5 through 7 (Table 5). Selenium concentrat ions in the outflow of wetland cells 1 and 2, the manganese oxidation basins, and final wetla nd cells averaged 7.4 mg/L, 6.8 mg/L, 6.8 mg/L, and 6.0 mg/L, respectively (Fig 8). After week 7, wetland cell 2 from both Trains A and B were modified by addition of organic ma tter; train C remained the same as previous weeks. Total selenium was then analyzed in the equalization basin and the outflow from wetland cells 1 and 2

in each train. Total selenium decreased from 6.3 mg/L in the equalization basin to an average of 3.8 mg/L for the outflow of cell 1 and 1.3 mg/L for the outflow of cell 2 (Fig. 8) in Trains A and

B. Total selenium in the final outflow wa s 0.78 mg/L and 0.88 mg/L from Trains A and B, respectively, compared to 2.10 mg/L from Train C (Table 5). Treatment trains improved during week 9 sampling and total selenium removal re ached 87% compared to the previous 84%.

High-Intermediate Ionic Strength FGD Wastewater

Before beginning week 11, the simulated FGD wa stewater was diluted with 40% municipal water reducing the chlorides to 4000 mg/L to allow for plant stability (health). Selenium removal averaged 87% between the A and B trains. Th e average outflow for 10 weeks (week 11 through- 16- week 20) was 0.56mg/L. The average outflow selenium concentrati on for train A was 0.47 mg/L, approaching the target outflow concentra tion of 0.4 mg/L. Trains B and C have averaged 0.64 and 0.68 mg/L, resp ectively (Fig. 10).

Low-Intermediate Ionic Strength FGD Wastewater

Analysis of selenium removal by the pilot co nstructed wetland system beginning week 23 indicated an average influent sele nium concentration of 1.87 mg/L ( ± 0.06) (Fig. 11). Final

outflow concentrations for week 23 for treatmen t trains A, B, and C were 0.20 mg/L, 0.09 mg/L, and 0.28 mg/L, respectively, or an overall removal of 90% (Figure 11). For week 24 sampling, total selenium influent concentrations averag ed 1.8 mg/L (no standard deviation). Outflow concentrations of selenium from the manganese oxidation basins (third tr eatment stage) reached the target level of 0.2 mg/L (Fi g. 12). Final outflow selenium c oncentrations increased slightly in trains A, B, and C (concentrations: 0.47 mg/L, 0.70 mg/L, and 0.41 mg/L, respectively).

Arsenic

High Ionic Strength FGD Wastewater

Total arsenic concentrations in the equalization basin averag ed 0.30mg/L, and ranged from 0.27 mg/L to 0.34 mg/L for weeks 5 through 7 (Table 5) . Arsenic concentrations in the outflows of wetland cells 1 and 2, the manganese oxidation ba sin, and the final wetl and cells averaged 0.6433 mg/L, 0.03588 mg/L, 0.0167 mg/L, and 0.0092 mg/L , respectively. Arsenic removal was not enhanced to a discernable degree following hydrosoil amendments to Trains A and B. Total As in final outflow of week 8 was 0.0870mg /L and 0.0840 mg/L from Trains A and B, respectively, compared to 0.0700 mg/L from Trai ns C (no amendments made to hydrosoil; Table 4). At the following sampling events, beginning week 10 performance of all treatment trains decreased, only removing 45% compared to 70%. Overall, performance of the pilot system treating undiluted simulated FGD wastewater was approximately 59 % removal of As (week 8 to week 10;Figure 13). Average inflow As concen tration for these two sampling events was 0.2983 mg/L compared to 0.1215 mg/L in the final outflow (Figure 13).

High-Intermediate Ionic Strength FGD Wastewater

After diluting the simulated FGD wastewater with 40% municipal water, As removal (average of treatment Trains A and B) was 49% (Figure 14). The average outflow As concentration from

weeks 11 to week 20 for these trains was 0.0832 mg/L. The average outflow As concentration for Train A was 0.0616 mg/L, below the target outf low concentration of 0.15mg/L. Trains B and C averaged 0.0982 and 0.087 mg/L, re spectively (Figure 14).

Low-Intermediate Ionic Strength FGD Wastewater

Analysis of arsenic removal by the pilot constructed wetland sy stems for week 23 indicated an average influent arsenic concentration of 0.075 mg/L ( ± 0.001) (Figure 15). Final outflow concentrations for week 23 sampling event for treatment trains A, B, and C were 0.043 mg/L, 0.012 mg/L, and 0.029 mg/L, respectively, or an overall removal of 62% (Figure 15). For week 24 sampling, total arsenic influent c oncentrations averaged 0.07 mg/L ( ± 0.003). Final outflow- 17- arsenic concentrations increased in trains A, B, and C (concentrations: 0.18 mg/L, 0.23 mg/L, and 0.11 mg/L, respectively) and is possibly due to binding of arsenic ont o particulates (total suspended solids) that is detect ed by total inorganic analysis.

Other Constituents of Interest

Simulated FGD wastewater physical and chemical characteristics are presented in Table 5. These parameters were analyzed at the following stages or locations in the pilot constructed wetland treatment system:

1. Equalization Basin

2. Outflow from the first wetland cell of each train (A-1, B-1, C-1)

3. Outflow from the second wetland cell of each train (A-2, B-2, C-2)

4. Outflow from the Manganese Oxidation Basin of each train (A-3, B-3, C-3)

5. Outflow from final wetland cell of each train (A-4, B-4, C-4)

pH, Alkalinity, and Hardness

In the equalization basin, pH, alkalinity, and hardness averaged 6.55 (n=2), 22 mg/L as CaCO 3 (n=2), and 4200 mg/L as CaCO 3 (n=2), respectively, for week 5 and week 6 of treatment. During the next three weeks of treatment (Weeks 7, 8, and 9) the pH, alkalinity, and hardness averaged 7.10 (n=3, sd=0.30), 106.67 mg/L as CaCO 3 (n=3, sd=21.39), and 9057 mg/L as

CaCO 3 (n=3, sd=1006.54). For the following ten weeks of treatment (Weeks 11 through 20) during which the simulated FGD wastewater wa s diluted, pH averaged 7.00 (n=10, sd=0.26), alkalinity averaged 103.40 mg/L as CaCO 3 (n=10, sd=10.46), and hardness averaged 6540 mg/L

as CaCO 3 (n=10, sd=2480.23). For the treatment of weeks 22 and 23, pH averaged 6.47, alkalinity averaged 115 mg/L as CaCO 3 and hardness averaged 7200 mg/L as CaCO 3 . For the last two treatment weeks, weeks 23 and 24, F GD wastewater was had an average pH 6.72, average alkalinity of 63 mg/L as CaCO 3 , and average hardness of 9800 mg/L as CaCO 3

.

In the first cell of the treatment system, pH , alkalinity, and hardness averaged 6.44 (n=6, sd=0.33), 22.33 mg/L as CaCO 3 (n=6, sd=3.44), and 3850 mg/L as CaCO 3 (n=6, sd=467.97), respectively, for weeks 5 and 6. During the next three weeks of treatme nt (week 7 through week 9) the pH, alkalinity, and hardness aver aged 7.32 (n=9, sd=0.17), 94 mg/L as CaCO 3 (n=9, sd=18.14), and 9022 mg/L as CaCO 3 (n=9, sd=603.69). For the following ten weeks of treatment (Weeks 11 through 20), during which the simulated FGD wastewater was diluted, pH averaged 7.07 (n=30, sd=0.23), alkalinity averaged 87.17 mg/L as CaCO 3 (n=30, sd=12.26), and hardness averaged 5373.33 mg/L as CaCO 3 (n=30, sd=1331.56). For the treatment of weeks 21 and 22, pH averaged 6.85 (n=6, sd=0.20), alkalinity averaged 112.33 mg/L as CaCO 3 (n=6, sd=1.97), and hardness aver aged 6266.67 mg/L as CaCO 3 (n=6, sd=206.56). For the last two treatment weeks, week 23 and 24, the FGD wast ewater had an average pH 6.79 (n=6, sd=0.06), average alkalinity of 69 mg/L as CaCO 3 (n=6, sd=5.48), and average hardness of 9800 mg/L as

CaCO 3 (n=6, sd=912.14).

In the second cell of the treatment system, pH, alkali nity, and hardness averaged 5.94 (n=6, sd=0.37), 15.33 mg/L as CaCO 3 (n=6, sd=4.84), and 3833 mg/L as CaCO 3 (n=6, sd=422.69),- 18- respectively, for weeks 5 and 6. During the next three weeks of treatment (Week 7 through 9) the pH, alkalinity, and hardness averaged 6.66 (n=9, sd=0.35), 98.22 mg/L as CaCO 3 (n=9, sd=33.11), and 8356 mg/L as CaCO 3 (n=9, sd=811.04). For the following ten weeks of treatment (week 11 through week 20), during whic h the simulated FGD wastewater was diluted, pH averaged 7.07 (n=30, sd=0.24), alkalinity averaged 88.93 mg/L as CaCO 3 (n=30, sd=17.39), and hardness averaged 5240 mg/L as CaCO 3 (n=30, sd=1580.39). For the treatment of week 21, pH averaged 7.34 (n=3, sd=0.20), alkalinity averaged 113.33 mg/L as CaCO 3 (n=3 sd=1.15), and hardness averaged 6000 mg/L as CaCO 3 (n=3, sd=400). For the last two treatment weeks, weeks 23 and 24, the FGD wastewater had an average pH 6.56 (n=6, sd=0.18), average alkalinity of 69.67 mg/L as CaCO 3 (n=6, sd=9.24), and average ha rdness of 10933.33 mg/L as CaCO 3 (n=6, sd=1377.92).

In the third cell of the treatment system, pH , alkalinity, and hardness averaged 7.21 (n=6, sd=0.19), 55 mg/L as CaCO 3 (n=6, sd=10.18), and 3783 mg/L as CaCO 3 (n=6, sd=495.65), respectively, for week 5 and week 6. During the next three week s of treatment (week 7 through week 9) the pH, alkalinity, and hardness averaged 7.22 (n=9, sd=0.32), 101.33 mg/L as CaCO 3 (n=9, sd=24.82), and 7867 mg/L as CaCO 3 (n=9, sd=489.89). For th e following ten weeks of treatment (week 11 through week 20), during whic h the simulated FGD wastewater was diluted, pH averaged 7.26 (n=30, sd=0.24), alkalinity averaged 90.67 mg/L as CaCO 3 (n=30, sd=15.04), and hardness averaged 5380 mg/L as CaCO 3 (n=30, sd=1238.85). For th e treatment of weeks 21 and 22, FGD wastewaters had a pH averaged 7.03 (n=6, sd=0.28), alkalinity averaged 104.67 mg/L as CaCO 3 (n=6, sd=4.50), and hardness averaged 5933.33 mg/L as CaCO 3 (n=6, sd=733.94). For the last two trea tment weeks, week 23 and 24, F GD wastewaters had an average pH 6.78 (n=6, sd=0.18), average al kalinity of 76.33 mg/L as CaCO 3 (n=6, sd=2.94), and average hardness of 11066.67 mg/L as CaCO 3 (n=6, sd=1671.73).

In the fourth cell of the trea tment system, pH, alkalinity, a nd hardness averaged 6.77 (n=6, sd=0.09), 56.33 mg/L as CaCO 3 (n=6, sd=14.39), and 3616.67 mg/L as CaCO 3 (n=6, sd=604.70), respectively, for weeks 5 and 6. During the next three weeks of treatme nt (week 7 through week 9) the pH, alkalinity, and hardness averag ed 7.27 (n=9, sd=0.26), 93.56 mg/L as CaCO 3 (n=9, sd=22.36), and 7244.44 mg/L as CaCO 3 (n=9, sd=904.31). For the following ten weeks of treatment (week 11 through week 20), during whic h the simulated FGD wastewater was diluted, pH averaged 7.24 (n=30, sd=0.27), alkalinity averaged 86.80 mg/L as CaCO 3 (n=30, sd=15.07), and hardness averaged 5846.67 mg/L as CaCO 3 (n=30, sd=1560.45). For th e treatment weeks 21 and 22, FGD wastewaters had a pH averaged 7.06 (n=6, sd=0.26), alkalinity averaged 110.33 mg/L as CaCO 3 (n=6, sd=3.44), and hardness averaged 6000 mg/L as CaCO 3 (n=6, sd=252.98).

For the last two treatment week s, week 23 and week 24, FGD wastewaters had an average pH 6.82 (n=6, sd=0.11), average alkalinity of 77.67 mg/L as CaCO 3 (n=6, sd=5.28), and average hardness of 10600 mg/L as CaCO 3 (n=6, sd=1356.47).

Conductivity

Conductivity measurements were 14.98 mS (n= 5, sd=0.79) for weeks 5 through 9 in the equalization basin. Outflow measurements fo r conductivity for this time period were 12.58 mS (n=15, sd=1.21). For the weeks in which the s imulated FGD wastewater was diluted, week 11 through week 20, the equalization basin averag ed 9.21 mS (n=10, sd=0.60) with the outflow averaging 9.27 mS (n=30, sd=1.25). For weeks 21 and 22, FGD wastewater s was diluted, with- 19- resulting conductivity measuremen ts of 11.06 mS (n=2) in the equalization basin and 10.89 mS (n=6, sd=0.58) in the outflow. In the last tw o weeks of treatment (w eek 23 and 24), conductivity measurements were 11.16 mS (n=2) in the equali zation basin and 11.89 mS (n =6, sd=2.27) in the

outflow.

NPOC (Non-Purgable Organic Carbon)

In the equalization basin, NPOC averaged 18.47 mg /L (n=2) for weeks 5 and 6. During the next three weeks of treatment (week 7 through week 10) NPOC averaged 99.72 (n=3, sd=43.22). For the following ten weeks of treatment (week 11 through week 20), during which the simulated FGD wastewaters was diluted, NPOC averaged 96.07 mg/L (n=10, sd=52.71). For the treatment

of week 21 and week 22 NPOC av eraged 106.97 mg/L (n=2). For the last two treatment weeks, week 23 and week 24, FGD wastewaters had an average NPOC of 161.25 mg/L (n=2).

In the first cell of the treatment system, NPOC averaged 11.60 mg/L (n=6, sd=1.80) for the first two weeks of treatment (week 5 a nd week 6). During the next th ree weeks of treatment (week 7 through week 10) the NPOC averaged 92.49 mg/L (n=9, sd=66.49). For the following ten weeks of treatment (week 11 through week 20), durin g which the simulated FGD wastewater was diluted, NPOC averaged 60.58 mg/L (n=30, sd= 32.16). For the treatmen t of 21 and 22, NPOC averaged 97.95 mg/L (n=3, sd=34.89). For the last two treatment week s, week 23 and 24, FGD wastewaters had an average NPOC of 61.76 mg/L (n=6, sd=41.25).

In the second cell of the treatment system, NPOC averaged 9.80 mg/L (n=6, sd=1.59) for the first two weeks of treatment (week 5 and week 6). During the next three weeks of treatment (week 7 through week 10) the NPOC averaged 75.62 mg/L (n=9, sd=46.59). For the following ten weeks of treatment (week 11 through week 20) , during which the simulated FGD wastewater was diluted, NPOC averaged 53.07 mg/L (n=30, sd=26.68). For the tr eatment of week 21, NPOC averaged 44.28 mg/L (n=3, sd=26.02). For th e last two treatment weeks, week 23 and 24, FGD wastewaters had an average NP OC of 47.96 mg/L (n=6, sd=7.74).

In the third cell of the treatment system, NPOC averaged 8.17 mg /L (n=6, sd=2.30) for the first two weeks of treatment (week 5 a nd week 6). During the next th ree weeks of treatment (week 7 through week 10) the NPOC averaged 61.21 mg/L (n=9, sd=33.83). For the following ten weeks of treatment (week 11 through week 20), durin g which the simulated FGD wastewater was diluted, NPOC averaged 47.42 mg/L (n=30, sd =21.91). For treatment of week 21, NPOC averaged 63.11 mg/L (n=3, sd=41.92). For the last two treatment week s, week 23 and 24, FGD wastewaters had an average NPOC of 43.72 mg/L (n=6, sd=16.35).

In the fourth cell of the treatment system, NPOC averaged 11.52 mg/L (n=6, sd=6.84) for the first two weeks of treatment (week 5 and week 6). During the next three weeks of treatment (week 7 through week 10) the NPOC averaged 43.99 mg/L (n=9, sd=13.71). For the following ten weeks of treatment (week 11 through week 20) , during which the simulated FGD wastewater was diluted, NPOC averaged 47.27 mg/L (n=30, sd=20.69). For the tr eatment of week 21, NPOC averaged 66.01 mg/L (n=3, sd=14.31). For th e last two treatment weeks, week 23 and 24, FGD wastewaters had an average NP OC of 38.12 mg/L (n=6, sd=18.97).- 20- Solids

Total suspended solids (TSS) was 7.40 mg/L fo r week 5 and 9.30 mg/L for week 6 in the equalization basin. For week 3 (week 7), TSS increased to 1,233 mg/L. Total dissolved solids (TDS) was 12,551 mg/L for week 5, 22,996 mg/L for week 6, and 22,080 mg/L for week 7 in the equalization basin. For weeks 9 and 10 (prior to diluting simulated FGD wastewater), TSS was 758 mg/L and 362 mg/L, respectively, and TDS av eraged 23,332 mg/L (n=2). For the weeks 11 through 20, the simulated FGD wastewater was dilu ted. TSS in the equalization basin averaged 207 mg/L (n=10, sd=137) and TDS averaged 6,184 (n=10, sd=2967). For weeks 21 and 22, FGD wastewaters was diluted, resulting in an aver age TSS in the equalization basin of 55 mg/L (n=2) and an average TDS of 12,534 mg/L (n=2). For the last two weeks of treatment (week 23 and 24), FGD wastewaters had a TSS and TD S averaged 66.5 mg/L (n=2) and 12,267 mg/L (n=2).

In wetland cell 1, TSS averaged 2.2 mg/L (n=3, sd=0.7) and 12.3 mg/L (n=3, sd=3.7) for week 5 and week 6 TDS averaged 16,699 mg/L (n=3, sd=1,027) for week 5 and 27,909 mg/L (n=3, sd=5,424) for week 6. For week 7, TSS and TDS averaged 9.7 mg/L (n=3, sd=2.0) and 21,672 mg/L (n=3, sd=1,214), respectivel y. Prior to diluting simulate d FGD wastewater during the weeks 9 and 10, TSS averaged 32.3 mg/L (n=6, sd=18.35) and TDS averaged 18,773 mg/L (n=6, sd=1315). For the following ten treatment w eeks (week 11 through week 20), the simulated FGD wastewater was diluted. TSS averaged 68 mg/L (n=27, sd=64.6; for week 19, TSS averaged 5,408, n=3, sd=566) and TDS averag ed 5,892 mg/L (n=30, sd=2,514). For weeks 21 and 22, TSS and TDS in wetland cell 1 averag ed 55 mg/L (n=6, sd=2.6) and 12,769 mg/L (n=6, sd=439), respectively. For w eek 23 and 24, TSS averaged 83 mg/L (n=6, sd=42) and TDS averaged 13,069 mg/L (n=6, sd=5,354).

In wetland cell 2, TSS averaged 1.2 mg/L (n=3, sd=1.4) and 7.35 mg/L (n=3, sd=2.1) for week 5 and week 6). TDS averaged 14,023 mg/L (n=3, sd=336) for week 1 and 21,615 mg/L (n=3, sd=3,251) for week 2. For the week of 9-15-04, TSS and TDS averaged 11.55 mg/L (n=3, sd=2.5) and 19,362 mg/L (n=3, sd=1130), respect ively. Prior to diluting simulated FGD wastewater during week 9 and w eek 10, TSS averaged 59 mg/L (n =6, sd=42) and TDS averaged 20,708 mg/L (n=6, sd=1,552). For the following ten treatment weeks (week 11 through week 20), the simulated FGD wastewater was diluted. TSS averaged 59 mg/L (n=30, sd=66) and TDS averaged 5,770 mg/L (n=30, sd=2,308). For we ek 21 and week 22, TSS and TDS in wetland cell 2 averaged 31 mg/L (n=6, sd= 12.7) and 9,324 mg/L (n=6, sd=432) , respectively. For week 23 and 24, TSS averaged 81 mg/L (n=6, sd=35) and TDS averaged 12,946 mg/L (n=6, sd=910).

In wetland cell 3, TSS averaged 2.42 mg/L (n=3, sd=1.0) and 5.93 mg/L (n=3, sd=2.2) for week 5 and 6. TDS averaged 17,765 mg/L (n=3, sd =1,447) for week 5 and 23,486 mg/L (n=3, sd=460) for week 6. For week 7, TSS and TD S averaged 6.45 mg/L (n=3, sd=1.86) and 18,677 mg/L (n=3, sd=269), respectively. Prior to di luting simulated FGD wastewater during week 9 and week 10, TSS averaged 34 mg/L (n=6 , sd=27) and TDS averaged 19,345 mg/L (n=6, sd=779). For the following ten treatment week s (week 11 through week 20), the simulated FGD wastewater was diluted. TSS averaged 59 mg /L (n=30, sd=56) and TDS averaged 5,736 mg/L (n=30, sd=3,854). For week 21 and week 22, TSS and TDS in wetland cell 3 averaged 51 mg/L (n=6, sd=20) and 12,851 mg/L (n=6, sd=748), resp ectively. For the weeks of week 23 and 24, TSS averaged 104 mg/L (n=6, sd=18) and TDS averaged 13,064 mg/L (n=6, sd=1,197).- 21- In wetland cell 4, TSS averaged 0.65 mg/L (n =3, sd=0.71) and 12.22 mg/L (n=3, sd=12.29) for week 5 and week 6. TDS averaged 16,180 mg/L (n=3, sd=849) for week 5 and 17,687 mg/L (n=3, sd=6,679) for week 6. For week 7, TSS and TDS averaged 6.95 mg/L (n=3, sd=2.8) and 18,939 mg/L (n=3, sd=624), respectively. Prior to diluting simulated FGD wastewater during week 9 and 10, TSS averaged 32 mg/L (n=6, sd=22) and TDS averaged 16,734 mg/L (n=6, sd=2,522). For the following ten treatment week s (week 11 through week 20), the simulated

FGD wastewater was diluted. TSS averaged 60 mg/L (n=30, sd=71) and TDS averaged 6,061 mg/L (n=30, sd=2,802). For week 21 and week 22, TSS and TDS in wetland cell 4 averaged 46 mg/L (n=6, sd=15) and 12,949 mg/L (n=6, sd= 893), respectively. For week 23 and 24, TSS averaged 103 mg/L (n=6, sd=46) and TDS averaged 12,289 mg/L (n=6, sd=603).

Chlorides

Chloride concentrations were 5,182 mg/L (n= 5, sd=242) for week 5 through week 9 in the equalization basin. For weeks 10 through 14, th e simulated FGD wastewater was diluted. Chlorides in the equalization basin averaged 3,463 mg/L (n=10, sd=464). For week 11 through week 20, FGD wastewaters had chloride concentr ation in the equaliza tion basin of 4,113 mg/L (n=2). For the last two weeks of treatment (week 23 and 24), chloride concentration in the equalization basin for week 23 was 4,150 mg/L. In wetland cells 1, 2, 3, and 4, chloride concentrations were not significantly different from the equalization ba sin during all treatment weeks from week 5 through week 24.

Sulfate

Sulfate concentrations were 747 mg/L (n=5, sd=373) for the firs t five treatment weeks (week 5 through 9) in the equalization basin. For the week 10 through week 14, the simulated FGD wastewater was diluted. Sulfates in the equa lization basin averaged 854 mg/L (n=10, sd=216). For week 11 through week 20, sulf ate concentration in the equalization basin of 664 mg/L (n=2).

For the last two weeks of treatm ent (week 23 and 24), the averag e sulfate concentration in the equalization basin the last two weeks was 432 mg/L (n=2). In wetland cells 1, 2, 3, and 4, sulfate concentrations were not significantly different from the equalization ba sin during all treatment week 5 through week 24.

Dissolved Oxygen, Biological Oxygen Demand, Chemical Oxygen Demand

In the equalization basin, dissolved oxygen (DO), biological oxygen demand (BOD), and chemical oxygen demand (COD) averaged 7.26 mg/L (n=5, sd= 1.9), 10.30 mg/L (n=5, sd=4.3), and 373 mg/L (n=3, sd=43.4), respectively, for w eeks five through week 9. For the following ten weeks of treatment (week 11 through week 20) , during which the simulated FGD wastewater was diluted, DO averaged 7.75 mg/L (n=10, sd=1.56), BOD averaged 14.06 mg/L (n=10, sd=5.24), and COD averaged 227 mg/L (n=10, sd= 45). For the treatmen t of week 21 and 22, DO averaged 7.95 mg/L and BOD averaged 9.63 mg/L . For the last two treatment weeks, week 23 and 24, FGD wastewaters had an average DO of 8.48 mg/L, av erage BOD of 10.48 mg/L, and average COD of 239 mg/L.

In the first wetland cell, DO averaged 8.19 mg/L (n=15, sd=0.95) for week 5 through week 9 prior to diluting the simulated FGD wastewater. For the treatment of week 5 and week 6, BOD- 22- averaged 1.88 (n=6, sd=0.46). For the treatment weeks 7, 9 a nd 10, BOD averaged 8.41 mg/L (n=3, sd=0.11), 12.09 mg/L (n=3, sd=0.58), and 19.83 mg/L (n=3, sd=3.27), respectively. For the treatment weeks 7 through 10, COD averaged 329 mg/L (n=9, sd=44). For the treatment weeks 11 through 20, the simulated FGD wastewater was diluted, re sulting in an average DO of 8.63 mg/L (n=30, sd=1.3) and average COD of 181 mg/L (n=30, sd=18). BOD averaged 12.65 mg/L (n=15, sd=5.7) for the weeks 11 through 15, and averaged 3.46 mg/L (n=15, sd=1.52) for the weeks16 through 20. For treatment weeks 21 and 22, DO averaged 6.81 mg/L (n=6, sd=0.33) and BOD averaged 8.46 mg/L (n=6, sd=1.1) . For the last two tr eatment weeks, (week 23 and 24). DO averaged 8.73 mg/L (n=6, sd=3.3 ), BOD averaged 2.92 mg/L (n=6, sd=1.8), and COD averaged 257 mg/L (n=6, sd=15).

In the second wetland cell, DO averaged 7.57 mg /L (n=15, sd=2.2) for weeks 5 through 9 prior to diluting the simulated FGD wastewater. Fo r the treatment weeks of, BOD averaged 1.51 (n=6, sd=0.9). For the treatment weeks 7, 9 and 10, BOD averaged 8.44 mg/L (n=3, sd=0.06), 6.34 mg/L (n=3, sd=0.92), and 21.32 mg/L (n=3, sd=1.16), respectivel y. For the treatment weeks 7 through 10, COD averaged 278 mg/L (n=9, sd=36). For the treatment weeks 11 through 20, the simulated FGD wastewater was diluted, result ing in an average DO of 8.69 mg/L (n=30, sd=1.1) and average COD of 177 mg/L (n=3 0, sd=33). BOD averaged 10.49 mg/L (n=15, sd=2.9) for the weeks11 through 15, and averag ed 3.43 mg/L (n=15, sd=2.1) for the weeks16 through 20. For the treatment weeks 21 and 22, DO averaged 6.19 mg/L (n=3, sd=0.07) and BOD averaged 6.55 mg/L (n=3, sd=0.34). For th e last two treatment weeks (weeks 23 and 24), DO averaged 8.71 mg/L (n=6, sd=3.3), BOD aver aged 4.78 mg/L (n=6, sd=1.7), and COD averaged 201 mg/L (n=6, sd=6.7).

In the third wetland cell, DO av eraged 7.36 mg/L (n=15, sd=1.9) for weeks 5 through 9prior to diluting the simulated FGD wastewater. For th e treatment weeks 5 and 6, BOD averaged 1.17 (n=6, sd=0.16). For the treatment weeks 7, 9 , and 10, BOD averaged 8.27 mg/L (n=3, sd=0.29), 7.44 mg/L (n=3, sd=0.5), and 15.46 mg/L (n=3, sd= 0.56), respectively. For the treatment weeks of7 through 10, COD averaged 253 mg/L (n=9, sd= 29). For the treatment weeks of11 through 20, the simulated FGD wastewater was diluted, result ing in an average DO of 8.84 mg/L (n=30, sd=1.4) and average COD of 163 mg/L (n= 30, sd=30). BOD averaged 8.37 mg/L (n=15, sd=2.66) for the weeks 11 through 15, and averaged 2.25 mg/L (n=15, sd=1.57) for the weeks of16 through 20. For the treatment weeks 21 and 22, DO averaged 6.72 mg/L (n=3, sd=0.25) and BOD averaged 3.45 mg/L (n=3, sd=1.96). For the last two treatment weeks (23 and 24), DO averaged 8.74 mg/L (n=6, sd=3.3), BOD averaged 1.94 mg/L (n=6, sd=0.74), and COD averaged 197 mg/L (n=6, sd=7).

In the fourth wetland cell, DO averaged 7.51 mg/L (n=15, sd=1.4) for weeks 5 through 9 prior to diluting the simulated FGD wastewater. For th e treatment weeks 5 and 6, BOD averaged 0.96 (n=6, sd=0.26). For the treatment weeks of 7, 9, and 10 BOD averaged 6.30 mg/L (n=3, sd=1.27), 6.40 mg/L (n=3, sd=0.14), and 10.76 mg/L (n=3, sd=7.00), respectively. For the

treatment weeks 7 throu gh 10, COD averaged 202 mg/L (n=9, sd=48). For the treatment weeks 11 through 20, the simulated FGD wa stewater was diluted, resul ting in an aver age DO of 8.74 mg/L (n=30, sd=1.35) and average COD of 159 mg /L (n=30, sd=48). BOD averaged 4.71 mg/L (n=15, sd=2.9) for the weeks 11 through 15, and averaged 1.92 mg/L (n=15, sd=1.35) for the weeks 16 through 20. For the treatment weeks 21 and 22, DO averaged 6.73 mg/L (n=3,- 23- sd=0.26) and BOD averaged 2.53 mg/L (n=3, sd=1.02) . For the last two treatment weeks (week 23 and week 24) DO averaged 8.72 mg/L (n=6, sd=3.3), BOD averaged 3.18 mg/L (n=6, sd=0.95), and COD averaged 184 mg/L (n=6, sd=8.29).

Hydrosoil Oxidation-Reduction (Redox) Potential

Hydrosoil redox potential from the pilot constructed wetland system is presented in Fig. 13 and Table 5. Cells 1 and 2 were designed to be anae robic, while cells 3 and 4 were designed to be essentially aerobic. Redox poten tial increased during wi nter months, but remained largely within the range of sulfate reduction (approximately –50 to –250 mV) in th e anaerobic cells (as designed) (Fig. 13).-24-Table 5.Simulated FGD wastewater physical and chemical properties analyzed in a pilotconstructed wetland system.Week 5Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin14.18 7.48 6.21 18 4000 14.82 6.85 ND 7.40 12551 18.41 0.3400 19.4 8.50 0.04600 4880 455A-1 17.56 6.55 6.09 20 3400 12.99 1.37 ND 1.45 17832 11.83 0.0150 14.4 6.50 0.00420 4490 708B-1 17.54 6.95 6.20 18 3400 13.49 1.35 ND 2.30 16436 9.72 0.0150 15.5 6.60 0.00340 4500 631C-1 17.08 7.56 6.15 20 3500 13.25 2.03 ND 2.85 15830 9.22 0.0170 15.8 6.90 0.00430 4010 667A-2 17.51 7.78 5.51 8 3700 12.80 0.80 ND 13788 8.08 ND 11.9 5.50 0.00170 4200 559B-2 16.45 4.67 5.57 12 3400 13.25 0.52 ND 0.90 13873 8.11 0.0059 13.5 6.30 0.00170 4370 557C-2 16.92 7.16 5.81 18 3300 12.89 0.85 ND 2.70 14408 9.01 0.0076 13.1 6.00 0.00170 4170 697A-3 14.12 10.53 7.57 60 3300 13.12 1.13 ND 2.05 16668 5.64 0.0190 12.4 5.80 0.00083 4310 576B-3 12.83 7.44 7.11 68 3400 13.79 1.43 ND 3.60 19405 6.79 0.0052 14.4 6.20 0.00067 4570 527C-3 13.19 8.02 7.26 64 3300 13.46 1.13 ND 1.60 17223 6.27 0.0096 13.4 6.00 0.00075 4330 607A-4 13.35 7.77 6.70 60 3000 11.76 0.59 ND 1.45 15523 6.18 0.0081 10.5 4.10 0.00041 3750 524B-4 12.78 7.40 6.65 74 3100 12.58 1.10 ND 0.40 17138 5.93 ND 12.7 5.50 0.00037 4260 516C-4 12.26 8.38 6.84 72 3100 12.20 1.37 ND 0.10 15878 5.60 0.0051 11.9 4.50 0.00033 4010 500Week 6Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin17.30 9.33 6.89 26 4400 14.46 8.83 ND 9.30 22996 18.52 0.2700 13.2 7.60 0.01300 5420 608A-1 17.03 9.72 6.86 26 4400 14.93 2.15 ND 14.45 23736 13.70 0.1100 15.5 7.90 0.00530 5650 656B-1 16.90 9.31 6.69 24 4100 14.82 1.82 ND 8.00 34040 13.18 0.0560 15.6 7.80 0.00440 5200 626C-1 16.40 9.70 6.63 26 4300 14.83 2.55 ND 14.45 25952 11.96 0.0970 16.3 8.20 0.00420 5310 668A-2 16.86 9.07 6.37 20 4200 14.85 2.72 ND 9.50 23698 11.52 0.0150 16.0 7.80 0.00260 5300.00 645.00B-2 16.60 9.25 6.06 14 4200 14.80 2.24 ND 7.30 23278 11.36 0.0086 15.0 7.70 0.00190 5520.00 626.00C-2 16.58 9.74 6.31 20 4200 14.96 1.91 ND 5.25 17868 10.71 0.0100 16.2 7.70 0.00170 5410.00 655.00-25-Table 4(Continued).A-317.289.017.2246420014.991.22ND7.75230649.180.012016.17.700.000825390.00632.00B-3 17.54 7.75 7.01 46 4300 14.93 1.18 ND 3.50 23418 9.54 0.0052 16.7 8.00 0.00091 5490.00 642.00C-3 18.00 7.57 7.08 46 4200 14.88 0.92 ND 6.55 23976 11.59 0.0072 15.4 7.70 0.00075 5510.00 625.00A-4 18.90 7.31 6.77 44 4200 14.02 0.96 ND 7.35 23724 13.69 0.0085 15.3 7.10 0.00093 5270.00 590.00B-4 18.85 7.47 6.79 42 4100 14.14 0.94 ND 26.20 18826 15.19 0.0050 15.7 7.40 0.00092 5210.00 527.00C-4 19.11 7.69 6.89 46 4200 14.20 0.80 ND 3.10 10512 22.54 0.0100 16.0 7.50 0.00099 5380.00 650.00Week 7Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin20.34 8.47 6.80 88 8000 14.96 7.79 384 1233.00 22080 63.42 0.3000 21.3 7.10 0.00190 5360 1180A-1 20.11 8.64 7.51 90 8400 15.61 8.52 387 9.85 22226 40.19 0.0710 22.1 7.30 0.00130 5810 1120B-1 20.49 8.54 7.06 56 9600 15.67 8.42 321 7.65 22510 24.96 0.0580 23.9 7.50 0.00270 6020 1090C-1 20.21 8.41 7.04 82 9600 15.40 8.30 300 11.60 20280 47.92 0.1400 22.9 7.40 0.00190 5600 1210A-2 20.30 8.50 6.75 64 8400 13.69 8.37 324 9.75 19903 40.71 0.0590 18.9 6.00 0.00160 4960 987B-2 20.21 8.62 6.93 68 8400 13.93 8.50 321 14.45 20120 41.87 0.0610 20.9 6.90 0.00200 4860 945C-2 20.43 8.59 7.00 74 8000 12.79 8.46 264 10.45 18063 47.65 0.1200 19.6 6.50 0.00230 4190 954A-3 20.15 8.63 7.07 80 8400 13.01 7.94 249 4.35 18893 37.27 0.0280 19.5 6.30 0.00110 4580 888B-3 20.48 8.60 6.94 80 8400 13.32 8.48 279 7.10 18376 39.22 0.0170 20.1 6.50 0.00120 4680 527C-3 20.65 8.54 7.06 84 8000 12.80 8.39 288 7.90 18761 44.67 0.0470 20.0 6.50 0.00140 4700 905A-4 19.88 8.69 7.26 84 8000 12.86 6.26 276 10.20 18285 35.84 0.0170 18.7 5.10 0.00064 4320 891B-4 20.36 8.64 7.02 76 8400 13.33 7.58 237 4.95 19527 35.89 0.0110 19.3 6.10 0.00079 4980 954C-4 20.42 8.60 7.10 82 8000 13.35 5.05 228 5.70 19005 35.40 0.0180 21.8 6.30 0.00077 4690 963Week 8Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LSe mg/LA-1 In 17.62 9.98 7.19 86 10400 15.09 8.04 310 5.80 22065 31.82 6.3000B-1 In 17.02 8.85 7.13 90 9200 14.82 7.95 303 8.85 20218 32.74 6.3000C-1 In 17.34 10.03 7.07 90 9200 15.14 8.83 - 6.65 20280 34.21 6.2000-26-A-117.6310.127.17921000016.445.242641.702236924.434.4000B-1 17.18 10.16 7.09 86 9600 16.33 4.99 250 9.65 22761 25.67 2.2000C-1 17.42 10.05 7.15 90 9600 16.31 4.92 236 4.65 23086 30.54 4.9000A-2 - - - - - - - - - - - 1.3000B-2 18.21 8.98 6.98 84 9600 16.71 8.25 252 5.90 23717 26.09 0.9700C-2 18.70 10.05 7.03 94 9600 16.75 2.94 235 2.30 23580 24.32 1.8000Week 9Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin18.13 6.63 7.09 102 10000 16.32 10.44 326 758.30 22902 88.21 0.2700 23.7 8.00 0.01500 5280 899A-1 In 17.62 8.01 7.30 104 9200 16.18 12.57 366 185.75 22814 86.07 0.3500 23.9 7.60 0.00710 5060 880B-1 In 17.47 8.12 7.19 92 9200 16.11 12.84 340 71.40 22834 76.36 0.3100 24.4 8.00 0.02200 5320 882C-1 In 17.73 8.37 7.28 90 9200 16.13 12.38 329 49.00 22752 75.99 0.2800 23.9 7.80 0.01700 5310 870A-1 17.38 8.45 7.28 94 9200 16.38 11.44 300 31.20 23076 62.75 0.2300 24.4 7.30 0.00820 5310 910B-1 17.25 7.86 7.33 98 9600 16.38 12.27 390 36.40 22322 54.64 0.2600 23.8 4.90 0.00600 5080 969C-1 18.02 8.51 7.34 98 9600 16.38 12.57 383 46.95 23157 63.31 0.2600 24.2 7.50 0.01100 5320 904A-2 18.22 3.87 6.98 118 9600 16.49 5.82 304 36.40 20800 63.63 0.2300 24.1 2.40 0.00330 5430 947B-2 17.44 4.15 6.60 72 8400 16.46 7.40 299 48.65 21834 53.31 0.1600 24.0 2.70 0.00360 5300 921C-2 18.44 4.03 6.96 94 9600 16.48 5.80 256 18.75 22759 50.57 0.1500 23.8 4.50 0.00340 5290 958A-3 18.39 4.23 7.01 102 8000 14.18 7.95 242 81.90 19747 50.55 0.1700 21.0 1.40 0.00160 4530 852B-3 18.06 4.35 7.02 94 7200 14.25 7.44 230 24.70 19828 46.50 0.1300 21.6 1.30 0.00150 4440 829C-3 18.32 4.07 7.00 88 8400 13.51 6.94 201 47.70 18587 39.50 0.1300 19.7 3.60 0.00350 4340 744A-4 18.85 4.99 7.12 82 5600 10.48 6.53 133 32.95 14123 37.41 0.0870 14.5 0.78 0.00096 3230 592B-4 19.21 5.54 7.09 72 6800 10.70 6.43 153 25.05 14990 31.90 0.0840 15.4 0.88 0.00092 3150 588C-4 19.65 4.50 7.04 78 6400 10.92 6.25 147 19.25 14279 34.12 0.0700 16.0 2.10 0.00170 3270 616-27-Week 10Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin21.57 4.39 7.40 130 9200 14.32 17.59 410 361.80 23763 147.53 0.3000 - 7.20 0.01600 4970 1340A-1 In 21.20 6.31 7.12 86 8400 14.35 21.32 330 46.20 22093 245.18 0.3000 - 7.60 0.00830 4930 1370B-1 In 22.00 6.40 7.14 84 8800 14.35 17.05 329 50.70 21.318 205.78 0.3000 - 7.80 0.00740 4960 1320C-1 In 21.49 7.51 7.06 116 8000 12.60 20.55 313 24.30 19118 203.02 0.2500 - 6.30 0.00830 4310 1140A-1 21.39 7.60 7.42 98 8400 13.37 22.89 282 11.50 20070 178.53 0.3000 - 2.80 0.00380 4650 1230B-1 21.55 7.76 7.50 122 8400 14.12 20.21 309 49.00 22295 189.41 0.5500 - 2.00 0.00360 4900 1280C-1 22.14 7.27 7.44 108 8400 13.34 16.38 293 18.80 20488 170.71 0.4700 - 1.90 0.00370 4590 1240A-2 21.52 8.16 7.72 158 8000 13.48 20.38 234 139.30 20005 70.74 0.1100 - 1.40 0.00160 4730 1050B-2 21.82 7.65 7.46 136 7200 13.62 20.96 270 53.70 21065 157.79 0.3300 - 1.60 0.00220 4650 1220C-2 22.17 7.22 7.45 100 7600 13.06 22.62 227 55.70 18264 154.28 0.2800 - 1.30 0.00230 4530 1240A-3 21.46 5.80 7.69 158 7600 13.09 14.82 285 15.30 19242 67.58 0.1400 - 1.30 0.00120 4550 1080B-3 21.98 7.69 7.69 114 7600 13.10 15.67 235 27.50 20347 141.59 0.2300 - 1.20 0.00150 4550 1190C-3 22.02 8.11 7.54 112 7200 12.59 15.88 269 7.80 18320 84.03 0.1500 - 0.98 0.00140 4320 1170A-4 21.45 8.68 7.50 130 6800 12.49 3.65 215 33.90 18491 56.82 0.1700 - 0.97 0.00096 4820 1050B-4 21.47 8.56 7.67 118 7600 13.17 17.64 234 72.50 19457 67.64 0.2300 - 0.96 0.00110 4650 1220C-4 22.17 8.47 7.62 120 7600 12.45 11.00 197 6.70 19063 60.92 0.0880 - 0.86 0.00096 4240 1110Week 11Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin19.33 8.63 7.40 122 10800 10.07 25.03 283 107.60 10745 91.72 0.1900 - 4.70 0.00210 3925 925A-1 In 19.53 8.33 7.21 102 9200 9.94 25.12 235 18.40 10244 85.81 0.1800 - 4.50 0.00270 3825 1046B-1 In 19.41 8.25 7.08 114 9200 10.13 24.97 265 20.10 10223 149.23 0.1700 - 4.20 0.00260 3825 1000C-1 In 19.68 8.27 7.21 108 9600 10.00 25.08 304 41.20 10600 84.39 0.1800 - 4.50 0.00270 3825 1058-28-A-118.528.377.409476009.4720.43171ND979865.690.2900-1.800.0024037501100B-1 18.29 8.92 7.19 106 5600 10.01 21.21 215 10.70 10481 59.27 0.3000 - 1.60 0.00230 3800 999C-1 18.91 8.39 7.31 96 6800 10.33 22.76 231 7.50 10922 58.25 0.2200 - 2.30 0.00180 3650 935A-2 18.31 9.09 7.54 140 7600 9.60 14.15 221 3.40 9592 42.83 0.0940 - 1.10 0.00086 3900 1016B-2 17.83 8.90 7.42 82 6400 8.15 13.31 186 1.60 8056 36.20 0.1100 - 1.20 0.00110 3250 765C-2 18.52 9.09 7.45 80 5600 8.09 10.96 169 4.10 8186 34.57 0.1500 - 1.10 0.00100 3025 731A-3 18.55 9.01 7.45 142 7200 9.60 7.02 134 3.20 9784 37.38 0.1100 - 0.77 0.00035 3625 1002B-3 17.71 9.23 7.55 100 6000 9.14 6.87 138 2.00 9412 34.71 0.1300 - 0.74 0.00038 3425 1007C-3 18.27 9.18 7.13 88 6800 8.68 6.48 153 8.90 8814 33.51 0.1800 - 0.57 0.00046 3025 861A-4 19.16 9.14 7.60 120 8800 10.31 2.83 117 1.60 10151 34.20 0.0550 - 0.52 <.0002 3625 1029B-4 18.69 8.53 7.35 90 8000 9.29 1.45 220 0.10 9874 31.14 0.0760 - 0.55 <.0002 3325 903C-4 18.90 8.94 7.43 66 8800 9.08 0.68 150 2.80 9135 31.12 0.1200 - 0.55 <.0002 3075 986Week 12Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin22.73 7.51 7.41 96 10000 9.51 15.56 279 193.50 10599 177.73 0.1900 - 4.60 0.00310 3325 990A-1 In 22.20 8.36 7.55 86 9200 9.38 10.67 222 24.20 9639 190.33 0.1800 - 4.50 0.00350 3625 1067B-1 In 21.82 8.38 7.65 86 9200 9.46 13.24 192 24.20 10267 169.85 0.1800 - 4.50 0.00310 3175 1154C-1 In 21.89 7.95 7.25 82 9200 9.46 14.84 212 17.90 10805 176.94 0.1600 - 4.30 0.00280 3300 1144A-1 21.89 7.32 7.73 80 8400 8.58 15.40 177 13.50 9173 114.13 0.1700 - 1.10 0.00190 3000 1017B-1 21.75 8.50 7.39 75 8800 9.27 11.29 193 3.90 9083 123.06 0.2000 - 1.90 0.00180 3125 1025C-1 21.79 7.78 7.12 78 6400 8.24 14.49 161 4.10 9819 109.50 0.2100 - 1.30 0.00130 3175 1103A-2 21.86 8.33 7.24 116 7600 8.92 14.31 221 54.00 10162 85.04 0.1200 - 0.66 0.00042 3350 850B-2 22.25 7.56 7.01 112 8800 9.61 10.13 236 6.40 9347 109.21 0.1800 - 0.98 0.00086 3300 1079C-2 21.63 8.36 6.78 76 7200 8.60 14.47 205 19.50 9615 94.34 0.2000 - 0.93 0.00081 3100 938A-321.998.347.568876007.6913.8222120.30828777.600.0680-0.500.000402850812B-3 21.81 8.44 7.30 76 6400 7.78 12.82 287 2.30 7803 71.76 0.1300 - 0.86 0.00071 2700 869C-3 21.44 8.54 7.70 80 6000 7.80 9.10 161 3.60 9197 75.63 0.1300 - 0.64 0.00056 3200 891A-421.468.587.7510076008.732.072976.60916955.720.0270-0.25<.00023500884-29-B-4 22.25 8.41 7.36 92 8400 9.33 4.37 224 50.80 10276 72.63 0.1600 - 0.51 0.00030 3350 956C-4 21.36 8.47 7.32 72 7200 8.61 5.27 194 63.40 10132 69.18 0.1700 - 0.57 <.0002 3325 891Week 13Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin21.17 7.91 7.06 104 9200 8.71 11.68 169 536.00 8894.5 165.64 0.1900 - 4.30 0.00410 4075 750A-1 In 20.38 7.97 7.09 88 6400 8.65 14.30 210 25.70 8892.5 152.19 0.1600 - 4.10 0.00170 3250 703B-1 In 21.04 7.87 7.10 98 6800 8.44 11.56 183 30.30 8827.5 143.99 0.1600 - 4.20 0.00190 3300 696C-1 In 20.28 8.00 7.10 80 5600 8.62 12.01 192 21.10 8677 150.40 0.1600 - 4.00 0.00160 3375 822A-1 20.51 8.01 7.37 62 5200 6.98 6.91 214 4.70 7206.5 97.98 0.1800 - 1.70 0.00090 3200 537B-1 20.65 8.02 7.28 90 7200 9.04 13.51 174 9.10 8694.5 109.15 0.1900 - 2.10 0.00084 3275 841C-1 20.26 8.01 7.33 60 4800 6.73 1.35 167 4.50 6696.5 51.58 0.1400 - 0.96 0.00091 2750 636A-2 20.22 8.34 7.35 96 6400 7.94 11.56 234 8.30 8054.5 79.62 0.1400 - 0.83 0.00030 - 740B-2 20.28 8.33 7.22 86 8400 8.15 10.89 141 8.60 8423.5 91.34 0.1800 - 1.20 0.00096 3350 719C-2 20.18 8.11 7.14 64 6800 6.70 10.55 221 9.90 6923.5 63.19 0.1800 - 0.75 0.00088 3050 741A-3 20.65 8.25 7.38 110 7600 8.53 8.28 173 5.50 8542.5 78.34 0.1000 - 0.29 <.0002 3225 801B-3 20.83 6.80 7.30 116 8000 8.85 9.83 146 2.50 8690.5 80.93 0.1700 - 0.54 0.00026 3400 685C-3 20.09 8.40 7.48 80 6000 6.56 3.88 148 3.20 6903.5 51.31 0.1800 - 0.48 0.00047 2900 863A-4 21.63 7.92 7.48 114 8800 9.61 4.44 203 2.80 9296.5 63.61 0.0490 - 0.26 <.0002 3475 442B-4 20.78 7.81 7.49 100 7600 9.24 3.05 100 1.40 9299.5 74.78 0.1300 - 0.51 <.0002 3600 782C-4 21.14 7.51 7.24 86 4400 8.61 4.10 77 14.20 8115.5 59.34 0.0770 - 0.54 0.00026 3400 708Week 14Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin14.0411.166.9911856008.6817.81169300.503782142.290.1900-4.500.002103750809A-1 In 14.48 12.48 6.97 104 5200 8.61 16.88 210 168.40 4044 125.14 0.1800 - 4.70 0.00150 2825 931B-1 In 13.48 12.29 6.92 102 5200 8.57 17.18 183 185.30 3680 135.74 0.1800 - 4.70 0.00150 2775 1020C-1 In 13.98 11.94 6.95 108 5200 8.60 15.93 192 185.90 4070 126.79 0.1800 - 4.80 0.00130 2725 913-30-A-1 13.52 12.36 7.03 104 5200 9.13 10.38 214 225.90 4536 112.44 0.1700 - 3.70 0.00100 2975 872B-1 12.96 12.30 7.03 106 4800 8.76 12.22 174 184.50 4087 102.06 0.2000 - 3.80 0.00062 2875 768C-1 13.64 12.44 7.01 104 4400 8.12 7.87 167 214.80 4180 77.29 0.1200 - 2.30 0.00078 2750 742A-2 13.60 11.67 7.13 112 5200 9.03 7.85 234 246.30 4352 86.92 0.0980 - 1.30 0.00051 3125 804B-2 13.83 11.38 6.93 90 4400 7.86 10.93 141 237.50 4068 94.66 0.0830 - 0.88 0.00045 2825 789C-2 13.55 12.02 7.13 112 4400 8.36 8.28 221 238.00 4947 81.65 0.1500 - 1.40 0.00048 2925 886A-3 13.77 12.69 7.55 108 5200 9.52 8.93 173 256.80 4984 73.05 0.0880 - 0.64 0.00029 3250 799B-3 13.34 12.47 7.57 104 5000 8.62 9.83 146 - - 71.37 0.1700 - 1.10 0.00030 2950 765C-3 12.66 12.62 7.08 82 4800 8.36 8.45 148 223.30 4621 72.17 0.0910 - 0.50 0.00028 3250 840A-4 12.20 12.25 6.85 114 5200 9.77 12.19 203 281.10 4880 65.38 0.1200 - 0.62 0.00020 3300 763B-4 12.53 12.69 7.26 96 5200 8.68 5.95 100 238.80 4446 71.11 0.1100 - 0.89 0.00023 3125 944C-4 13.30 12.69 7.18 90 5200 8.79 5.59 77 231.20 4512 65.28 0.0660 - 0.47 0.00020 3000 760Week 15Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LBmg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin23.23 7.25 6.82 92 5200 9.84 15.05 213 148.40 3734.5 117.11 0.2000 - 4.70 0.00072 2525 1242A-1 In 22.92 7.66 6.90 88 5200 9.48 14.37 180 - 3292.5 94.17 0.2000 - 4.70 0.00094 2975 1260B-1 In 22.40 7.62 6.77 92 5200 9.69 13.74 180 55.50 2957.5 89.15 0.1900 - 4.50 0.00071 3235 1276C-1 In 22.65 7.76 6.95 88 5200 9.78 15.38 189 43.70 3753.5 86.22 0.2000 - 4.90 0.00074 3240 1261A-1 22.92 7.66 6.90 88 5200 9.48 14.37 180 - 3292.5 94.17 0.2000 - 4.70 0.00094 2975 1260B-1 22.21 7.92 6.83 96 5600 9.98 11.53 165 31.90 3670.5 79.47 0.1900 - 2.50 0.00055 3175 1324C-1 22.75 8.08 6.95 94 5600 10.04 11.93 188 38.90 3776.5 67.48 0.1900 - 2.40 0.00063 3360 1345A-2 22.28 8.20 6.95 106 5600 10.30 8.01 173 32.00 4553.5 65.43 0.2400 - 1.10 0.00010 3450 1371B-2 22.07 8.22 6.98 102 5600 10.17 8.00 185 58.20 4252.5 65.74 0.1700 - 1.40 0.00024 3450 1324C-2 22.32 8.57 6.85 90 5600 10.40 3.93 179 35.20 3842.5 64.39 0.0880 - 0.73 0.00028 3485 1337A-3 22.07 8.22 6.98 102 5600 10.17 8.00 185 58.20 4252.5 65.74 0.1700 - 1.40 0.00024 3450 1324B-3 22.08 8.35 7.00 102 6000 10.41 8.17 191 57.20 3990.5 66.63 0.2400 - 0.65 0.00010 3465 1245C-3 21.65 8.49 7.00 102 6000 10.21 7.67 180 38.30 3855.5 60.75 0.2100 - 0.69 0.00010 3450 1360A-4 22.00 8.54 7.01 112 6200 11.02 3.64 183 47.20 4172.5 56.89 0.0780 - 0.43 0.00010 3585 1348B-4 22.26 8.34 7.04 94 6200 10.80 7.91 165 22.00 4610.5 76.67 0.2300 - 0.88 0.00010 3635 1369-31-C-4 22.24 8.39 6.86 82 6200 10.75 7.16 195 30.20 4644.5 74.28 0.1000 - 0.51 0.00010 4390 1327Week 16Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin23.25 7.79 6.79 100 6000 9.94 15.82 184 72.20 5797.5 88.14 0.1600 - 3.90 0.00200 3725 1119A-1 In 22.56 8.27 6.83 94 5200 9.97 10.47 179 84.10 5132.5 68.10 0.1600 - 4.20 0.00260 3815 1095B-1 In 22.80 7.28 6.83 92 5200 9.97 6.91 174 110.50 4151.0 66.36 0.1500 - 4.00 0.00240 3250 1072C-1 In 21.68 7.62 6.80 90 5200 10.02 5.98 179 96.20 5278.5 56.97 0.1600 - 4.00 0.00270 3650 1079A-1 22.18 8.25 6.87 84 5200 10.32 2.65 174 69.20 6267.5 59.50 0.1700 - 2.80 0.00110 3850 1086B-1 22.01 8.13 6.85 94 5600 10.28 4.01 165 161.60 5873.5 57.55 0.1800 - 2.70 0.00140 3425 1129C-1 21.30 8.34 6.87 82 6400 12.25 2.88 183 69.50 6811.5 47.74 0.1100 - 1.20 0.00074 4825 1452A-2 21.81 8.53 6.90 92 6000 10.75 2.10 165 73.30 6488.5 49.55 0.0690 - 0.90 0.00054 3625 1181B-2 22.13 8.33 6.87 88 5600 10.48 1.87 165 62.80 6134.5 49.66 0.1300 - 1.80 0.00074 3500 1170C-2 22.70 8.24 6.65 78 4800 11.17 1.16 156 77.00 6403.5 37.87 0.0330 - 0.21 0.00010 4425 1285A-3 22.32 8.33 7.03 100 5600 11.07 1.32 165 53.00 5748.5 46.69 0.0500 - 0.36 0.00022 3750 1222B-3 21.98 8.05 6.90 86 5600 10.45 6.92 165 58.70 5723.5 49.88 0.1000 - 0.51 0.00032 4100 1109C-3 22.16 8.42 6.90 78 5600 10.58 4.00 152 70.90 6373.5 44.73 0.1400 - 0.38 0.00035 3750 1243A-4 21.86 8.44 6.92 84 6400 11.74 0.57 170 98.70 6026.5 47.40 0.0280 - 0.37 0.00010 4375 1307B-4 22.22 8.26 6.93 80 5200 11.01 3.72 164 44.60 6530.5 48.75 0.0540 - 0.46 0.00025 3625 1229C-4 21.57 8.36 6.88 80 4800 11.77 2.72 194 86.50 6701.5 46.00 0.0410 - 0.43 0.00030 4375 1355Week 17 Temp C DO mg/L pH Alk mg/L Hard mg/L Cond mS BOD mg/L COD mg/L TSS mg/L TDS mg/L NPOC mg/L As mg/L B mg/L Se mg/L Hg mg/L Chloridemg/LSO4 mg/LEqual.Basin21.24 6.65 7.19 96 4000 9.09 13.78 210 138.05 4965 48.47 0.1700 - 4.00 0.00094 3575 819A-1 In 21.87 7.67 6.97 84 4400 9.12 7.23 176 112.35 5187 53.97 0.1600 - 4.20 0.00640 3500 609B-1 In 22.14 6.87 6.95 78 4400 9.11 9.49 169 64.65 5074 56.94 0.1600 - 4.10 0.00490 3200 772C-1 In 20.92 7.40 7.02 86 4800 9.11 6.08 173 84.15 5172 58.46 0.1500 - 4.00 0.00420 3575 764A-1 21.40 8.34 6.90 76 3600 9.39 3.02 164 80.75 5077 37.85 0.1300 - 3.50 0.00170 3450 767B-1 22.04 8.27 7.16 92 4800 9.35 2.32 163 77.85 5446 31.94 0.1600 - 3.20 0.00160 3250 793-32-C-1 21.02 8.35 7.02 88 4800 9.31 2.01 164 98.65 4915 36.09 0.1300 - 3.20 0.00160 3325 789A-2 21.08 8.11 6.62 66 3600 7.11 5.83 162 53.95 4088 40.97 0.0700 - 1.20 0.00083 2825 658B-2 22.06 7.78 6.81 76 3200 6.38 7.35 163 48.85 3840 44.62 0.1200 - 1.60 0.00085 2525 579C-2 21.89 7.83 7.01 68 4000 6.10 7.22 164 56.25 3285 47.04 0.0970 - 1.30 0.00091 2525 842A-3 22.28 8.26 7.38 76 4000 7.96 1.27 156 56.45 4309 27.89 0.0360 - 0.41 0.00010 2975 821B-3 21.07 8.34 7.18 86 4000 8.78 1.99 160 79.85 4680 27.70 0.1300 - 0.49 0.00010 3225 767C-3 22.03 8.24 7.17 74 4000 7.82 1.58 159 81.45 3946 29.10 0.1000 - 0.71 0.00037 2650 696A-4 21.52 8.33 7.25 84 5200 9.36 1.24 165 81.75 4710 28.13 0.0220 - 0.34 0.00010 3300 895B-4 22.65 8.14 7.37 80 4400 9.53 0.82 160 92.55 5113 26.66 0.0610 - 0.61 0.00010 3325 880C-4 20.91 8.43 7.21 80 4800 9.55 0.53 150 45.55 5017 27.46 0.0490 - 0.56 0.00010 3350 924Week 18Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin22.71 5.02 6.82 92 4400 9.18 7.42 256 240.90 5660 53.66 0.1200 - 3.80 0.00400 3500 655A-1 In 23.08 5.80 7.21 82 4400 9.07 8.12 225 68.90 4624 48.91 0.1100 - 3.70 0.00300 3400 651B-1 In 22.56 6.04 6.80 66 4000 9.02 9.95 236 63.20 4387 50.30 0.1000 - 3.70 0.00350 3450 678C-1 In 23.03 6.52 6.90 70 4400 9.03 12.60 238 66.80 4370 45.44 0.1100 - 3.70 0.00240 3350 678A-1 22.67 8.00 7.01 70 4000 9.07 4.55 187 62.90 4069 35.28 0.0920 - 3.60 0.00120 3575 648B-1 22.83 8.10 7.13 74 4000 8.95 1.80 195 48.00 4776 31.36 0.0970 - 2.90 0.00110 3325 640C-1 23.11 7.92 7.15 86 4400 9.15 5.42 201 52.80 5565 33.22 0.1000 - 3.40 0.00120 3625 711A-222.258.286.997036009.145.7516675.60542630.660.0540-0.710.000403475752B-2 22.54 8.26 7.01 70 3600 9.17 1.96 176 55.70 5667 31.44 0.1000 - 1.70 0.00069 3725 720C-2 23.15 8.24 6.95 72 4000 9.26 3.64 176 47.70 4221 28.80 0.1100 - 2.40 0.00083 3625 722A-3 23.04 8.55 7.05 76 4000 9.15 2.31 165 45.80 5222 27.12 0.0190 - 0.27 0.00010 3575 709B-3 23.61 8.51 6.92 78 4000 9.17 3.29 170 51.10 4575 27.53 0.0390 - 0.52 0.00025 3675 746C-3 24.25 8.61 6.94 76 4000 9.15 3.08 175 153.00 4305 - 0.0940 - 1.50 0.00036 3425 905A-4 23.14 8.21 6.90 70 4800 7.67 2.30 176 53.00 4214 - 0.0340 - 0.58 0.00010 3125 706B-4 23.04 7.96 6.98 58 4400 7.07 4.76 172 40.30 4030 - 0.0760 - 0.71 0.00024 2850 604C-4 22.69 8.25 6.96 60 4400 7.60 3.65 165 41.50 4346 - 0.0850 - 0.99 0.00027 3000 648-33-Week 19Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin22.01 7.30 6.83 104 5200 8.54 7.01 235 95.85 5670 34.83 0.1600 - 4.10 0.00360 3250 559A-1 In 21.98 7.93 7.21 96 4800 8.60 5.70 193 108.65 5768 34.60 0.1600 - 4.10 0.00450 3225 523B-1 In 22.17 7.54 7.43 90 5200 8.53 4.83 189 44.55 5728 44.84 0.1500 - 4.60 0.00510 3050 502C-1 In 22.53 7.32 7.38 88 5200 8.88 5.98 190 - 5756 41.71 0.2100 - 4.50 0.00290 3225 793A-1 21.64 8.25 7.05 80 4800 8.99 5.96 169 47.66 5029 31.48 0.1400 - 3.70 0.00180 3225 524B-1 21.38 8.19 6.90 84 4800 8.93 5.62 173 38.45 6059 29.64 0.1500 - 3.50 0.00089 3075 590C-1 22.36 8.02 6.72 80 5200 8.62 5.30 176 29.35 5137 27.05 0.1600 - 3.20 0.00150 3200 621A-2 21.69 8.36 7.42 82 4000 8.66 2.75 156 39.55 5295 20.11 0.0260 - 0.37 0.00039 3050 560B-2 21.65 8.11 6.90 84 3600 8.12 3.28 142 27.05 5406 20.89 0.0720 - 1.20 0.00082 3100 549C-2 22.24 7.99 7.32 84 4000 8.71 2.37 150 32.25 5948 26.52 0.1200 - 2.20 0.00110 3100 584A-3 22.52 7.84 7.63 90 4800 8.47 1.62 156 42.45 5598 19.75 0.0240 - 0.28 0.00010 3025 583B-3 22.16 8.01 7.36 86 4400 8.66 1.03 150 32.75 5535 23.98 0.0530 - 0.43 0.00031 3200 545C-3 22.12 7.96 7.54 80 5200 9.05 1.47 152 35.75 5400 22.82 0.0690 - 1.40 0.00045 3250 610A-4 22.96 7.44 7.22 84 4800 9.32 1.02 150 36.25 5876 19.31 0.0120 - 0.26 0.00010 2975 602B-4 22.50 7.65 7.05 80 4000 8.85 0.74 140 39.35 5817 20.57 0.0280 - 0.44 0.00010 3175 606C-4 20.79 8.29 7.30 78 4800 9.30 0.61 125 51.65 6047 21.69 0.0520 - 1.30 0.00023 3400 600Week 20Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin22.88 8.23 6.69 110 5000 8.50 11.47 276 237.40 1991 41.09 0.1700 - 4.10 0.00120 2975 670A-1 In 21.94 8.35 6.71 104 5200 8.29 2.12 219 105.80 1930 28.70 0.1500 - 4.10 0.00310 3025 646B-1 In 21.14 8.45 6.75 106 4800 8.30 2.54 199 81.00 1593 28.84 0.1700 - 4.40 0.00400 3000 607C-1 In 20.78 8.60 6.80 104 4800 8.46 2.73 205 424.00 1785 29.80 0.1600 - 4.30 0.00270 2950 699A-1 20.27 8.70 6.72 98 3600 8.62 2.35 176 61.00 1774 23.61 0.2600 - 2.90 0.00230 3025 738B-1 19.82 8.81 6.92 98 4000 8.94 2.35 168 110.90 2039 20.93 0.0860 - 1.60 0.00055 3175 779C-1 20.10 8.83 6.89 98 4000 8.63 1.70 166 22.40 2022 20.14 0.1500 - 2.40 0.00130 3200 623-34-A-2 20.55 8.75 7.06 94 4000 8.60 2.21 125 20.60 2395 25.15 0.0940 - 1.70 0.00080 3200 645B-2 19.82 8.80 7.35 90 3600 8.73 1.74 138 17.60 2171 22.80 0.0970 - 1.90 0.00071 3100 664C-2 19.95 8.85 7.08 90 4000 8.74 2.21 137 29.87 1837 20.80 0.2200 - 2.40 0.00090 3175 680A-3 19.97 8.92 7.27 92 3600 8.56 1.50 129 20.20 1809 23.60 0.0430 - 0.47 0.00023 3175 702B-3 19.70 8.85 7.24 90 4000 8.60 1.50 145 16.66 2049 24.35 0.1200 - 1.30 0.00056 3075 662C-3 20.06 8.80 7.30 90 4400 8.68 0.91 142 16.80 2075 22.38 0.1800 - 1.00 0.00034 3125 678A-4 20.47 8.72 7.70 86 4400 8.07 2.86 116 74.30 2026 20.25 0.1500 - 1.10 0.00010 2875 664B-4 20.27 8.77 7.66 86 4800 7.48 1.76 110 13.30 1332 - 0.0870 - 0.83 0.00023 2925 550C-4 20.26 8.79 7.60 86 4400 7.21 1.56 98 20.00 1333 21.39 0.1500 - 0.87 0.00010 2750 597Week 21Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin24.43 7.58 6.56 120 7600 10.97 9.11 NA 51.05 12449 106.97 0.0025 - 0.06 0.00010 4100 673A-1 In 23.51 6.46 6.76 122 7600 12.47 12.06 NA 57.15 14844 62.47 0.0051 - 0.07 0.00010 5125 773B-1 In 23.34 6.34 6.79 120 7200 12.82 11.29 NA 60.25 14726 122.58 0.0025 - 0.09 0.00010 4850 818C-1 In 23.29 6.49 6.77 122 7200 12.79 12.12 NA 55.95 15296 160.48 0.0025 - 0.13 0.00010 4850 816A-1 23.46 7.53 7.04 116 6400 11.44 9.74 NA 53.25 14905 64.18 0.0200 - 0.12 0.00010 4325 713B-1 23.25 7.55 7.05 112 6400 11.40 7.19 NA 54.55 15448 95.80 0.0220 - 0.09 0.00010 4400 746C-1 23.52 7.95 7.00 112 6400 11.44 7.06 NA 56.55 14871 133.88 0.0120 - 0.11 0.00010 4425 711A-2 23.66 8.18 7.16 114 5600 10.19 6.93 NA 45.65 8826 71.82 0.0180 - 0.11 0.00010 3925 560B-2 24.13 8.30 7.30 112 6400 6.65 6.43 NA 24.35 9556 40.91 0.0150 - 0.08 0.00010 2725 462C-2 24.11 8.29 7.56 114 6000 4.65 6.28 NA 22.95 9590 20.10 0.0410 - 0.64 0.00010 1875 427A-3 25.55 7.53 7.20 108 6000 11.15 6.75 NA 88.85 11916 110.63 0.0083 - 0.08 0.00040 4225 741B-3 24.86 7.75 7.22 108 6800 10.19 2.13 NA 39.45 13187 47.31 0.0370 - 0.12 0.00010 3900 867C-3 24.95 7.58 7.40 110 6800 7.28 1.57 NA 32.35 13856 31.39 0.0690 - 0.32 0.00021 2750 620A-4 24.97 7.61 7.19 112 6400 11.65 4.27 NA 70.25 12241 80.12 0.0640 - 0.14 0.00010 4425 903B-4 24.89 7.73 7.31 114 5600 11.33 2.49 NA 46.05 12844 51.51 0.0120 - 0.13 0.00010 4200 1019C-4 24.66 7.57 7.35 114 6000 10.44 2.59 NA 51.35 14123 66.39 0.0300 - 0.25 0.00010 3800 799-35-Week 22Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin22.65 8.31 6.37 110 6800 11.15 10.15 NA 58.80 12618 NA 0.0025 - 0.06 0.00010 4125 655A-1 In 22.49 8.24 6.49 114 6400 13.43 13.56 NA 42.00 14923 NA 0.0025 - 0.07 0.00010 4825 921B-1 In 22.10 8.35 6.48 112 6400 13.80 12.57 NA 35.60 14871 NA 0.0025 - 0.12 0.00010 5150 848C-1 In 21.78 8.12 6.50 114 6000 13.05 13.12 NA 43.70 15534 NA 0.0025 - 0.08 0.00010 4250 865A-1 21.08 8.07 6.60 112 6400 12.73 8.79 NA 51.90 14108 NA 0.0089 - 0.10 0.00010 4725 711B-1 20.95 8.31 6.73 112 6000 11.70 8.91 NA 58.90 14987 NA 0.0170 - 0.13 0.00027 4375 837C-1 20.86 8.23 6.68 110 6000 12.22 9.08 NA 53.20 15063 NA 0.0086 - 0.10 0.00010 4550 823A-2 - - - - - - - - - - - - - - - - -B-2 - - - - - - - - - - - - - - - - -C-2 - - - - - - - - - - - - - - - - -A-3 20.62 7.96 6.78 100 5600 9.01 4.37 NA 57.20 12019 NA 0.0270 - 0.14 0.00010 3500 596B-3 21.06 8.04 6.79 102 5200 9.52 3.85 NA 49.00 12967 NA 0.0170 - 0.06 0.00010 3675 500C-3 20.76 8.15 6.79 100 5200 8.76 2.01 NA 41.56 13158 NA 0.0450 - 0.14 0.00010 3400 548A-4 20.74 8.12 6.85 106 6000 10.86 2.81 NA 49.20 11987 NA 0.0350 - 0.12 0.00010 3925 743B-4 20.61 7.95 6.91 108 6400 10.06 1.49 NA 32.00 12548 NA 0.0120 - 0.06 0.00010 3875 628C-4 21.81 8.16 6.72 108 6000 10.99 1.53 NA 29.30 13952 NA 0.1500 - 0.05 0.00035 3900 688Week 23Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin19.93 8.59 6.88 58 12800 9.43 11.03 241 65.05 12536 228.52 0.0730 - 1.80 0.16000 4150 407A-1 In 19.84 8.66 6.80 58 13000 9.31 2.46 256 82.80 13543 88.81 0.0740 - 1.80 0.13000 3975 406B-1 In - - 6.79 60 11600 9.39 3.62 232 95.45 13977 57.54 0.0760 - 1.90 0.14000 4100C-1 In 19.55 8.58 6.85 58 10800 9.79 1.98 237 93.55 13358 22.34 0.0750 - 1.90 0.14000 4150 392A-1 19.79 8.73 6.73 78 11600 9.32 2.58 269 75.95 13994 130.49 0.0500 - 1.50 0.04300 4175 440B-1 19.51 8.72 6.82 72 10000 7.78 1.64 238 61.40 14631 81.86 0.0530 - 0.30 0.03600 3475 446-36-C-1 19.90 8.65 6.83 70 12800 9.62 5.63 255 66.30 14392 22.66 0.0600 - 1.70 0.04900 4350 454A-2 20.64 8.53 6.55 64 11600 10.74 7.21 199 63.75 11495 37.24 0.1600 - 0.58 0.04300 3750 332B-2 19.84 8.68 6.34 80 9600 9.57 3.87 206 82.80 13853 56.77 0.0580 - 0.20 0.02800 3525 445C-2 20.21 8.65 6.33 54 8800 7.72 4.63 194 109.30 13796 55.65 0.0410 - 0.30 0.01100 2525 418A-3 19.73 8.85 6.75 80 11600 11.31 2.04 205 123.60 12719 12.53 0.0560 - 0.14 0.01500 4100 488B-3 19.45 8.95 6.54 80 8400 9.54 1.98 186 116.75 12161 54.67 0.0130 - 0.06 0.00640 3175 457C-3 19.56 8.79 6.60 76 9600 10.13 2.39 193 108.10 13566 54.09 0.0850 - 0.25 0.01100 3800 420A-4 19.56 8.80 6.83 76 10400 11.08 2.81 179 87.50 12646 ND 0.0430 - 0.20 0.00720 4150 449B-4 20.14 8.66 6.72 74 8800 8.99 3.14 186 99.85 12554 42.03 0.0120 - 0.09 0.00100 3475 470C-4 19.95 8.80 6.65 70 9200 9.67 3.36 181 64.25 13058 57.11 0.0290 - 0.28 0.00690 3775 516Week 24Temp CDO mg/LpHAlk mg/LHard mg/LCond mSBOD mg/LCOD mg/LTSS mg/LTDS mg/LNPOC mg/LAs mg/LB mg/LSe mg/LHg mg/LChloridemg/LSO4 mg/LEqual.Basin20.13 8.37 6.55 68 12400 12.88 9.92 236 67.75 11998 93.98 0.0710 - 1.80 0.16000 - 457A-1 In 19.56 8.52 6.59 66 12400 13.14 0.84 233 80.35 12178 44.79 0.0690 - 1.80 0.16000 5175 458B-1 In 20.25 8.57 6.68 64 12000 13.13 4.40 229 122.35 12770 62.81 0.0730 - 1.80 0.17000 5325 485C-1 In 20.65 8.46 6.71 64 12400 13.06 2.44 245 136.65 11818 55.88 0.0680 - 1.80 0.17000 - 495A-119.768.796.69661200012.343.2427565.75856224.460.0820 - 1.30 0.11000 5100 547B-1 19.56 8.85 6.79 68 11600 12.78 1.04 241 62.65 13396 41.72 0.0490 - 0.41 0.04100 5025 543C-1 20.84 8.64 6.85 68 11600 13.38 11.12 264 168.85 13436 69.36 0.0640 - 1.60 0.05100 4950 553A-2 19.37 8.80 6.73 74 12000 12.09 5.32 202 98.05 13182 44.74 0.0400 - 0.21 0.02000 4700 566B-2 19.62 8.86 6.67 72 12000 12.46 2.04 210 61.65 13058 50.83 0.0570 - 0.34 0.03200 4725 598C-2 19.18 8.76 6.72 74 11600 13.51 5.60 193 72.05 12298 42.52 0.0350 - 0.33 0.01900 5300 621A-3 20.09 8.71 6.97 74 12400 12.87 0.48 199 88.85 13970 40.42 0.0270 - 0.10 0.00860 4975 531B-3 19.63 8.45 6.88 74 12400 12.97 2.36 197 77.05 14588 54.68 0.0240 - 0.14 0.00960 5000 577C-3 19.35 8.67 6.91 74 12000 13.84 2.40 204 111.45 11380 45.95 0.0170 - 0.21 0.01200 5250 595A-4 19.44 8.72 6.89 82 11600 13.93 3.60 193 190.25 11374 43.38 0.1800 - 0.47 0.00690 5075 580B-4 19.91 8.75 6.87 84 11600 13.67 4.52 193 105.15 11852 45.81 0.2300 - 0.70 0.00710 5650 647C-4 19.72 8.61 6.94 80 12000 14.01 1.64 172 70.05 12252 38.82 0.1100 - 0.41 0.00800 5525 649- 37- 0 0.005

0.01 0.015

0.02 0.025

0.03 0.035

0.04 0.045

0.05

In flo

w
Outfl o w Cell 1

Ou tf l o w Ce ll 2 Outfl o w MOB Final Ou t flow Cel l 4Total Mercury (mg/L)

Week 1 Week 2 Week 3

Figure 3. Total mercury in simulated FGD wastew ater treated by a pilo t constructed wetland system during the acclimation period (Weeks 1 to 4).

0 0.002 0.004 0.006 0.008

0.01 0.012 0.014 0.016

I nflo w

Ou t flow Cell 1 Outflow Cell 2

O ut

flow MO B

Final Out

f l ow

C

el

l 4Total Mercury (mg/L)

Train A Train B Train C

Figure 4 . Average total mercury in simulated FGD wastewater treated by a pilot constructed wetland system for the high ionic stre ngth FGD wastewater (Weeks 9 and 10).- 38- 0 0.0005

0.001 0.0015

0.002 0.0025

0.003 0.0035

Inflo w

Outf l ow Cell 1

O u tf l ow Cell 2
Outf l ow M O

B

Fin al

Ou

t flow C ell 4Total Mercury (mg/L)

Train A Train B Train C

Figure 5 . Average total mercury in simulated FGD wa stewater treated by a pilot constructed wetland system for the high-intermediate ioni c strength FGD wastewater (Weeks 11 to 20).

0 0.02 0.04 0.06 0.08

0.1 0.12 0.14 0.16 0.18

Inflow

O utflo w Ce

ll

1 Outflow Cell 2

O utf

lo w M O

B

Fin al Ou

tflo

w C e ll 4Total Mercury (mg/L)

Train A Train B Train C

Figure 6 . Total mercury in simulated FGD wastewat er treated by a pilot constructed wetland system for the first week of low-intermedia te ionic strength FGD wastewater (Week 23).- 39- 0 0.02 0.04 0.06 0.08

0.1 0.12 0.14 0.16 0.18

I nf

low Outflow Cell 1 Outflow Cell 2

Out f low

MOB Final Out f low Cell 4Total Mercury (mg/L)

Train A Train B Train C

Figure 7 . Total mercury in simulated FGD wastew ater treated by a pilo t constructed wetland system for the second week of low-intermedia te ionic strength FGD wastewater (Week 24).

0.00 1.00 2.00 3.00 4.00 5.00 6.00 7.00 8.00 9.00

Inf low

Outf low Cell 1

Out f low Ce l l 2

Out flow M

OB Final Outflow Cell 4Total Selenium (mg/L)

Week 1 Week 2

Week 3 Week 4

Figure 8 . Total selenium in simulated FGD wastewater treated by a pilot constructed wetland system during the acclimation period (Weeks 1 to 4).- 40- 0 1 2 3 4 5 6 7 8 9

Inf l o w

Outf l ow C ell 1

O u tf l ow

C ell 2

Out flow MOB Final Out f lo

w

C ell

4Total Selenium (mg/L)

Train A Train B Train C

Figure 9 . Average total selenium in simulated FGD wastewater treated by a pilot constructed wetland system for the high ionic stre ngth FGD wastewater (Weeks 9 and 10).

0 0.5

1 1.5

2 2.5

3 3.5

4 4.5

5

Inf l o w Outflow Cell 1

Out flow Cell 2 Outflow M OB Final Outflow C ell 4Total Selenium (mg/L)

Train A Train B Train C

Figure 10 . Average total selenium in simulated FGD wastewater treated by a pilot constructed wetland system for the high-intermediate ioni c strength FGD wastewater (Weeks 11 to 20).- 41- 0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.6 1.8

2

I n f lo

w Outflow C el

l 1 Outflow Cell 2

O utflow MO B

Fina l Ou t f low

C

ell

4Total Selenium (mg/L)

Train A Train B Train C

Figure 11 . Total selenium in simulated FGD wastew ater treated by a pilot constructed wetland system for the first week of low-intermedia te ionic strength FGD wastewater (Week 23).

0 0.2 0.4 0.6 0.8

1 1.2 1.4 1.6 1.8

2

Inflow

O u tf l ow

Ce

ll

1

O u tflow Cell 2 Outflow MOB

Fi n a l O

utfl

o w Ce l l 4Total Selenium (mg/L)

Train A Train B Train C

Figure 12. Total selenium in simulated FGD wastew ater treated by a pilot constructed wetland system for the second week of low-intermedia te ionic strength FGD wastewater (Week 24).- 42- 0 0.05

0.1 0.15

0.2 0.25

0.3 0.35

0.4 0.45

Inflo w

O u t fl

o w C e ll

1 Outflow Cell 2

O u t f low MOB

Fi n al

O

u t f l o w C

el

l 4Total Arsenic (mg/L)

Train A Train B Train C

Figure 13 . Average total arsenic in simulated FGD wastewater treated by a pilot constructed wetland system for the high ionic stre ngth FGD wastewater (Weeks 9 and 10).

0 0.02 0.04 0.06 0.08

0.1 0.12 0.14 0.16 0.18

0.2

Infl ow

O ut f l ow

Cel

l 1

O ut f low

Cel

l 2

O ut f l ow MOB

F i nal

O

utflow Cel l 4Total Arsenic (mg/L)

Train A Train B Train C

Figure 14 . Average total arsenic in simulated FGD wastewater treated by a pilot constructed wetland system for the high-intermediate ioni c strength FGD wastewater (Weeks 11 to 20).- 43- 0 0.02 0.04 0.06 0.08

0.1 0.12 0.14 0.16 0.18

In f low Outflow C

e l l 1

Out flo

w C

e l l 2 Outflow MOB

F in al

Out

flo

w

Cell 4Total Arsenic (mg/L)

Train A Train B Train C

Figure 15 . Total arsenic in simulated FGD wastewat er treated by a pilot constructed wetland system for the first week of low-intermedia te ionic strength FGD wastewater (Week 23).

0 0.05

0.1 0.15

0.2 0.25

I n f l o w Outflow C e l l 1

Outf l o w C

e l l 2

Ou t fl ow

M

O B

F i n al

Ou

tflow C ell

4Total Arsenic (mg/L)

Train A Train B Train C

Figure 16. Total arsenic in simulated FGD wastew ater treated by a pilo t constructed wetland system for the second week of low-intermediate ionic strength FGD wa stewater (Week 24).- 44- 

### Train A

-250 -200 -150 -100

-50

0 50 100 150 200

August September October November December JanuaryEh (mvolts) 

### Cell 1 Cell 2 Cell 3 Cell 4

Figure 17 . Hydrosoil oxidation-reduction (redox) pot ential for Train A of the FGD pilot-scale constructed wetland system.



### Train B

-200 -150 -100

-50

0 50 100 150 200

August September October November December JanuaryEh (mvolts) 

### Cell 1 Cell 2 Cell 3 Cell 4

Figure 18 . Hydrosoil oxidation-reduc tion (redox) potential for Train B of the FGD pilot-scale constructed wetland system.- 45- 

## Train C

-250 -200 -150 -100

-50

0 50 100 150

August September October November December JanuaryEh (mvolts) 

### Cell 1 Cell 2 Cell 3 Cell 4

Figure 19 . Hydrosoil oxidation-reduc tion (redox) potential for Train C of the FGD pilot-scale constructed wetland system.

Table 6 . Hydrosoil oxidation-reducti on (redox) potential in the FGD pilot constructed wetland system. Each redox value represen ts a mean of two measurements.

Redox Potential (mV) Redox Potential (mV)

Treatment

Week Cell A

Train B Train C

Train Treatment

Week Cell A Train B Train C Train

1 - 4 1 -105 -80 -83 14 - 17 1 -46 -26 -25

2 -61 -70 -45 2 -120 -81 -107

3 13 56 51 3 117 115 117

4 84 70 65 4 138 134 127

5 - 9 1 -125 -144 -121 18 - 22 1 -3 11 -148

2 -126 -117 -142 2 1 -98 -55

3 28 35 43 3 -89 28 9

4 89 70 85 4 58 57 102

10 - 13 1 -115 -138 -91 23 - 24 1 -113 -9 -182

2 -205 -158 -222 2 -112 -71 -68

3 32 5 7 3 -22 90 95

4 66 59 100 4 83 144 124- 46- 

### Discussion

Wastewater constituents of primary concern in this study were mercury, arsenic, and selenium. These constituents and others were analyzed inthe pilot constructed wetland treatment system for approximately six months using simulated F GD wastewater. During this time, the effects of manipulation and modifications of wetland hydrosoil, hydroperiod, and vegetation were evaluated. These manipulations and various initial wastewat er conditions have provided information for deriving removal rate coefficien ts necessary for determining adjustments to the system to achieve target outflow levels for these constituents.

The initial wetland cells in the series, planted with bulrush and amended with gypsum to provide sulfur ligands, effectively decreased the aqueous concentrations of mercur y and arsenic dissolved in the simulated FGD wastewater. Hydrosoil re dox of wetland cells 1 and 2 (A, B, and C) and aqueous pH indicated that conditions were favo rable for dissimilatory sulfate reduction, which provides reduced sulfide for precipitating availabl e cationic metals such as mercury and arsenic (Brookins, 1988; Morse, 1995; Carbonell et al., 1999).

“Redox” is a term used to de note oxidation-reduction. In simple terms, oxidation is loss of electrons by a substance and reduction is the gain of electrons. Every oxidation is accompanied by a reduction, and vice versa. In wetland hydros oil, redox may be meas ured to indicate the propensity for certain reactions to occur in that sediment or hydrosoil. Redox potential (Eh) is typically measured in hydrosoils and sediment s by using platinum electrodes and a portable voltmeter. Redox potential is a useful measur e of sediment or hydrosoil conditions. In a constructed wetland treatment syst em, multiple measurements of redox potential are required to

achieve an accurate esti mate for this parameter (bulk sediment redox potential) within each cell.

From site to site within a we tland cell, redox potential can vary widely due to localized conditions (e.g. the presence of a root or root hair near an electr ode). It is the general redox condition within the hydrosoil of the wetland cell that is of interest in order to maintain predictable reactions and behaviors of targeted co nstituents in the hydrosoil. Therefore, the range of redox potential measurements is an importa nt functional control parameter for operating constructed wetlands treatment systems in a pred ictable manner. For oxidizing conditions, redox potentials greater than –50 mV are appropriate for th e desired chemical reactions of this research (iron oxyhydroxide precipitates and decreases in COD and BOD). For mildly reducing conditions, redox potentials between -50 and –250 mV are the desirable redox ranges for elemental immobilization (sorption and precipitatio n) by reductive chemical pathways. Redox in constructed wetlands can be controlled by water depth and sediment amendments or composition (sediment oxygen demand).

Precipitated metal-sulfide minerals are highly insoluble in aqueous systems, which can significantly limit the availability of elements to a quatic and terrestrial biot a, or in other terms, decreasing bioavailability of these elements (M orse, 1995). In anaer obic sediments and wetland hydrosoils, mercury is strongly asso ciated (i.e. bond or electrosta tic attraction) by the following binding mechanisms: (1) sorption on hydrated ferric oxides, (2) surface sorption or ion exchange on mineral ion exchangers such as montmorillon ite, and (3) sorption and/or chemical binding with organic material and sulfur-containing matter. Given an adequate source of sulfide, mercury

will convert to a stable mercuric sulfide (HgS) with limited ava ilability to aquatic plants and animals (Fagerstrom and Jernelov, 1972).- 47- The preliminary design of the pilot constructe d wetland system included several features for

selenium removal from FGD wastewater. Not un like other wastewater constituents, alterations in the form of selenium affect solubility and in fluence mobility, transport, and fate in wetland environments. At pH and redox conditions occurri ng in many aqueous and aerobic sedimentary environments, selenium exists as a soluble oxyani on. In strongly reduced environments, selenide (Se ( - II)), dominantly exists as H 2 Se and as insoluble metal sele nides (Masscheleyn and Patrick, 1993). With modifications to wetland cell 2 (add ition of organic matter and zero-valent iron),

enhancement of selenium removal was obser ved. Under reducing conditions in wetlands,

elemental selenium and/or metal selenides a nd selenium-containing sulfur minerals govern selenium solubility. Reduction of Se (VI) to Se (IV) and Se (IV) to insoluble Se 0 or Se (-II) is expected to occur under the reduced hydrosoil conditions formed by the addition of organic matter. The pilot constructed wetland system was designed to provide conditions under which insoluble selenium species (e.g., Se 0 or Se ( - II)) are likely to form (Masscheleyn et al., 1990; Masscheleyn and Patrick, 1993). In addition, zero-vale nt iron was added to wetland cell 2 and the final wetland cell (i.e. cell 4) to comple x the residual selenium in the wastewater.

Chloride levels were not a ppreciably decreased by the pilot constructed wetland system. Chloride is not adsorbed by wetland hydrosoil but is readily transported in aqueous phase through the system (Murray-Guld e and Rodgers, 2002). Chloride is taken up by the roots and moves upward to accumulate on s hoots and leaves; however, these concentrations of chlorides within aquatic vegetation do not significantly affect the aqueous concentration as previously mentioned. Symptoms for chloride toxicity are leaf “burn” or a dr ying of leaf tissues. Some burn of the shoot and leaf tips was observed in the pilot constructed wetland system, indicating that salinity levels in the simulated FGD wastewater were approaching the salinity tolerance threshold for these plants. As a result, the simulated wastewater was diluted to 60% with municipal water. The wetland vegetation responded positively to the dilution.

Before the start of the low-intermediate ioni c strength FGD wastewat er (Week 23), further hydrosoil modifications were ma de and HRT was increased to 30 hours per treatment stage (120 hours overall). Under these condit ions, mercury removal was 96 to 97%, but only achieved the target outflow level of 0.001 mg/L in train B during week 23. Selenium removal achieved the target level of 0.2 mg/L during the treatment of the low-intermediate ionic strength FGD wastewater (weeks 23 and 24).



### Conclusions

Evaluation of the pilot constructed wetland system clearly indicates that mercury, arsenic, and

selenium concentrations in FGD wastewater are significantly decreased usi ng this design. Target outflow concentrations of mercury and selenium are achievable, as indicated by favorable responses in treatment performance following adjustments to the pilo t constructed wetland

system.- 48- 

### REFERENCES

American Public Health Association (APHA), American Water Works Association, and Water

Pollution Control Federation. 1998. Standard Methods for Examination of Water and Wastewater, 20 th Ed. American Public Health Association, Washington, D.C. Brookins, D.J. 1988. Eh-pH Diagrams for Geoche mistry. Springer-Verlag Berlin Heidelberg, New York, NY. Carbonell, A.A., Porthouse, J.D., Mulbah, C.K., Delaune, R.D., and Patrick, W.H., Jr. 1999. Metal solubility in phos phogypsum-amended sediment under controlled pH and redox conditions. J. Environ. Qual., 28, 232. Fagerstrom, T. and A. Jernelov. 1972. Some as pects of the quantitative ecology of mercury.

Water Res. 6: 1193-1202. Faulkner, S.P., W.H. Patrick, Jr., R.P. Gambre ll. 1989. Field Techniques for Measuring Wetland

Soil Parameters. Soil Sci. Soc. Am. J. 53: 883-890. Masscheleyn, P.R., R.D. Deluane, and W.H. Patrick, Jr. 1990. Tr ansformations of selenium as affected by sediment oxidation-reduction poten tial and pH. Environ. Sci. Tech. 24:91-

96. Masscheleyn, P.H. and W.H. Patrick, Jr. 1993. Biogeochemical processes affecting selenium cycling in wetlands. Environ. Tox. Chem.12:2235-2243. Morse, J.W. 1995. Dynamics of Trace Metal Inte ractions with Authigenic Sulfide Minerals in

Anoxic Sediments. In Metal Contaminated Aquatic Sediments. H. E. Allen (Ed.), Ann Arbor Press, Inc., Ann Arbor, MI. Murray-Gulde, C.L. and J.H. Rodgers, Jr. 2002. Phase II Constructed We tland Pilot Tr eatability Study On Kern River Produced Water. A Report To: Jim E. Myers, PE, Texaco Worldwide E&P, Technology Depa rtment, 1111 Bagby, Houston, Texas 77002.- 49- Scientific Final Report



### TASK 2

Introduction

The second objective of this re search was to determine how the observed performance of the pilot scale constructed wetland treatment system was achieved by investigating the reactions taking place in the sediments.

In a constructed wetland treatment system de signed to treat constituents of flue gas desulfurization (FGD) wastewat er, sediment becomes a sink for trace elements such as Hg, Se, and As. Determining total concentrations of these constituents in sediment cannot provide the required information about mobility, bioavailabi lity, and the potential impact on the aquatic system (Michalke, 2003). The distribution of Hg, Se, and As in the

constructed wetland treatment system depends on their speciation. Speciation defines a specific form of an element as to isotopic co mposition, electronic or oxidation state, or molecular structure (MITE, 2003). Speciation ca n greatly affect the fate and behavior of elements in this system, especially of t hose elements that exist in multiple oxidation states, such as Hg, Se, and As. These elements tend to form species differing from those

of other metals.

Sequential extraction procedures have been wi dely used to provide critical information on the fate of trace elements in aquatic systems (Tessier et al,. 1979). These procedures extract trace elements from sediment with increasing reagent strengths to break down

sediment matrices and release bound metals into soluble forms with the extractant (solvent) used in each step. While this pro cess cannot be used to identify the actual form of a given metal in sediment, sequential extrac tions are useful in categorizing the metals into geochemical fractions (McLean and Bled soe, 1992). Operationally-defined species

characterization is the characte rization of molecule groups (n ot single species) according

to their similar behavior duri ng an analytical procedure, su ch as extraction (Michalke, 2003).



### Materials and Methods

Sequential extraction procedures have been developed for mercury (Lechler et al., 1997; Wallschläger et al., 1998; Bloom et al., 2003; Beldowski and Pempkowiak, 2003), selenium ( Chao and Sanzolone, 1989 and Wang and Chen, 2003), and arsenic (Miller et
al ., 1986; Wenzel et al., 2001; Schank, 2003; Bird et al., 2003), utilizing common operationally-defined geochemical fractions to define the distribution of these metals in

sediment. One fraction extracted is the wa ter-soluble fraction, wh ich contains species made up of free ions and ions complexe d with soluble organic matter and other constituents. Element species in this frac tion are the most mobile and potentially the most bioavailable species. A nother is referred to as the exchangeable fraction, which corresponds to the form of elements that can be most readily rel eased into the water

column. This fraction includes elements that are weakly adsorbed to solid surfaces and elements that can be released by ion-excha nge processes. Generally, elements in the- 50- soluble and exchangeable fractions are considered readily and potentially bioavailable (Filgueiras et al ., 2002).

Two additional fractions extr acted from sediment are th e reducible and oxidizable fractions, both of which are re latively stable under normal we tland sediment conditions.

The reducible fraction includes elements bound to Fe and Mn oxides, which are often found in large proportions in sediments. The reduction and dissolution of Fe(III) and Mn(IV) will release adsorbed trace elements . The oxidizable fraction includes element species that may be associated with various forms of or ganic matter through complexation. The degradation of organic matter, including de tritus, under oxidized

conditions can lead to the release of trace elements bound to this component. These two fractions are not considered very mobile or bioavailable (Filgueiras et al ., 2002).

The last fraction utilized in this research is the residual fraction, which includes species associated with the crystallin e lattice structures of primar y minerals and silicates. Species in this fraction can only be naturally mobilized as a result of weathering. In sequential extraction procedures , this fraction can be mobili zed with a very strong acid, such as hydrofluoric acid (Filgueiras et al ., 2002).

By categorizing Hg, Se, and As into these geochemical fractions, hypotheses regarding reactions occurring in sediment in the cons tructed wetland treatment system can be tested. Furthermore, extrac tions of these element specie s are crucial for understanding metal biogeochemical behavior in constructed wetlands for FGD wastewater treatment.

Sequential extraction procedures (as outlin ed in Tables 7-9) were employed to operationally-define the species of Hg, Se, and As in the sediment. Concentrations of Hg, Se, and As in sediment fractions were measured according to the standard method EPA 200.8 (USEPA, 1994) using a Sciex Elan 9000 Inductively Coupled Plasma- Mass Spectrometer (ICP-MS) (Perkin-Elmer, Norwalk, CT). Sediment characteristics including pH, redox, cation exchange capaci ty (CEC), organic matter, solids, and pa rticle size

distribution were measured. Sediment pH, which is often one of the most important factors controlling speciation and equilibria for many contaminants, was measured using an YSI pH meter. Redox potential was meas ured using a digital millivolt meter and platinum-tipped electrodes prior to removi ng sediment samples from the wetland cell to

avoid false measurements due to sediment dist urbance. Particle size distribution analyses yielded three fraction sizes: sand, silt, and clay. The hydrometer method was used, as described by Gee and Gauder (1986). Percent solids of the sediment were measured according to Black (1986). The percent of or ganic matter in the sediment was measured using the lost-on-i gnition method, as described by Ne lson and Sommers (1996). Cation exchange capacity (CEC) of sediment is a measure of the reversib ly bound cations in the sample. CEC was determined according to methods presented by Plumb (1981).- 51- 

### RESULTS

Table 7 . Summary of sequential extraction proc edures for Hg (modified from Lechler et
al. 1997).

Fraction Description Extraction

1 Elemental (Heating at 180 o C) 2 Exchangeable 0.5 M MgCl 2 3 Reducible 0.5 N HCl

4 Oxidizable 0.3 N NaOH / 4% CH 3 COOH 5 Residual (Subtraction from total Hg)

Table 8. Summary of sequential extraction me thod for Se (modified from Chao and Sanzolone 1989).

Fraction Description Extraction

1 Soluble; nonspecifically adsorbed 0.25 M KCl 2 Exchangeable; specifically adsorbed 0.1 M KH 2 PO 4 3 Reducible 4 M HCl

4 Oxidizable KClO 3 and HCl

5 Residual HNO 3

Table 9 . Summary of sequential extraction pro cedure for As (modified from Wenzel et
al. 2001 and Schank 2003).

Fraction Description Extractant

1 Soluble; nonspecifically sorbed 0.05 M (NH 4 ) 2 SO 4 2 Exchangeable; specifically sorbed 0.05 M (NH 4 ) 2 H 2 PO 4 3 Reducible 0.2 M NH 4 -oxalate buffer; pH 3.25

4 Oxidizable 0.2 M NH 4 -oxalate buffer + 0.1 M ascorbic acid; pH 3.25

5 Residual HNO 3 /aqua regia

Sediment characteristics, including redox poten tial, pH, cation exchange capacity (CEC), percent organic matter (OM), percent solids, and particle size dist ribution, are listed in Table 9. The redox potentia ls of sediment in the fi rst and second wetland cells were -410 mV and -337 mV, respectively. Sediment in the fourth wetland ce ll had a redox potential- 52- of -26 mV. Measurements of sediment pH ranged from 6.63 to 6.80, and the cation exchange capacity of sediment ranged from 4.63 me 100g -1 to 6.83 me 100g -1 . Percent organic matter and percent solids in a ll sediments ranged from 1.95% to 2.52%, and 74.67% to 79.14%, respectively. According to the particle size distribution of the sediments, a majority of the sediment was sa nd, with small fractions of clay and silt.

Results from the sequential extractions of H g, Se, and As are summarized in Figure 20. The total sediment concentrations of Hg, as determined by the summation of individual fraction concentrations, were 0.0686 mg/kg, 0.0383 mg/kg, and 0.0282 mg/kg in the first, second, and fourth wetland cell, respectively. Mercury is primarily in its elemental

fraction in the sediment. Unless the sedime nt is strongly oxidi zed, mercury in this

fraction will remain immobile and will not be bi oavailable to plants and organisms. Total

sediment concentrations of Se were 9.353 mg/kg, 19.891 mg/kg, and 16.609 mg/kg in the first, second, and fourth wetland cell, resp ectively. Selenium is distributed amongst soluble, exchangeable, reducible, oxidizable , and residual fractions. Selenium is a required micronutrient; therefore, these results are not surprising. In a system containing large plant densities, selenium is likely to be readily available for plant uptake. Finally,

total sediment concentrations of As were 25.87 mg/kg, 24.92 mg/kg, and 25.84 mg/kg in the first, second, and fourth wetland cell. For the most part, arsenic is not bioavailable to plants and organisms, as it resides pr imarily in the residual fraction.

Table 10. Summary of sediment characteristics.

Particle Size Distribution

Sediment pH Redox a CEC b % OM c % Solids % Sand % Clay % Silt

First wetland cell 6.74 -410 6.83 2.5% 79.1% 91.4% 5.5% 3.0%

Second wetland cell 6.63 -337 4.63 1.9% 78.8% 91.5% 5.5% 2.9%

Third wetland cell 6.80 -26 5.08 2.2% 74.6% 89.2% 5.6% 5.1%

a Redox potential, measured in millivolts

b Cation exchange capacity (me 100g -1 )

c Organic matter- 53- Figure 20. Sequential extraction of Hg (A), Se (B), and As (C) in sediment collected from the first, second, and fourth planted wetland cells. 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

1st Wetland Cell 2nd Wetland Cell 4th Wetland Cell Residual

Oxidizable

Reducible

Exchangeable

Elemental

A

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

1st Wetland Cell 2nd Wetland Cell 4th Wetland Cell Residual

Oxidizable

Reducible

Exchangeable

Soluble

B

0%

10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

1st Wetland Cell 2nd Wetland Cell 4th Wetland Cell Residual

Oxidizable

Reducible

Exchangeable

Soluble

C- 54- 

### Discussion and Conclusions

Sequential extraction procedures were used as a quantitative measure to evaluate the

immobilization of these elements of concer n in the sedimentary component of these systems. Data gathered by this procedure indicate that the majority of As, Hg, and Se are bound to residue phases within the sediment, meaning that the dissolution or re-solubility of these elements are unlikely to occur under natural environmental conditions set within this treatment system (not thermodynamically favored). Mercury was observed to exist in two main phases: the residual and elemental, both of which are highly insoluble in the aqueous media and relatively stable in terms of transfers and transformations to any other phase, except for further transfers into th e residual phase. Most selenium existed in phases that should not contribute to bioavailability or toxicity, but this will be further

confirmed with sediment toxi city experiments. Arsenic concentrations were highly correlated with the residual phase within th ese sediments and should not elicit toxicity effects due to its binding stability. Data co llected from these expe riments are utilized along with toxicity tests to conf irm bioavailability parameters.- 55- REFERENCES

Beldowski, J. and Pempkowiak, J. 2003. Ho rizontal and vertical variabilities of mercury concentration and speciation in sediments of the Gdansk Basin, Southern

Baltic Sea. Chemosphere . 52, 645-654. Bird, G., Brewer, P.A., Macklin, M.G., Balteanu, D., Driga, B., Serban, M., and Zaharia, S. 2003. The solid state partitioning of contaminated metals and As in river channel sediments of the mining affec ting Tisa drainage basin, northwestern Romania and eastern Hungary. Appl. Geochem . 18, 1583-1595. Black, W.C. 1986. Methods of Soil Analysis Part 1. Second Edition, American Society of Agronomy. Madison, WI. Bloom, N.S., Preus, E., Katon, J., Hiltner, M. 2003. Selective extractions to assess the biogeochemically relevant fractionation of inorganic mercury in sediments and

soils. Anal. Chim. Acta . 479, 233-248. Chao, T.T. and Sanzolone, R.F. 1989. Extrac tion of soil selenium by sequential partial

dissolution. Soil Sci. Soc. Am. J. 53, 385-392. Filgueiras, A.V., Lavilla, I., and Bendic ho, C. 2002. Chemical sequential extraction for metal partitioning in environment solid samples. J. Environ. Monit . 4, 823-857. Gee, G.W., and Gauder, J.W. 1986. Particle-Size Analysis. In: Methods of Soil Analysis Part 1. Second Edition, Americ an Society of Agronomy. Madison, WI.

383-410. Lechler, P.J., Miller, J.R., Hsu, L.C., and Desilets, M.O. 1997. Mercury mobility at the Carson River Superfund Site, west-centr al Nevada, USA: interpretation of mercury speciation data in mill tailings, soils, and sediments. J. Geochem. Exploration . 58, 259-267. McLean, J.E. and Bledsoe, B.E. 1992. Behavior of metals in soil. In: USEPA Office of Research and Development. Ground Water Issue . EPA/540/S-92/018, October

1992.

Metals in the Environment (MITE) Research Network. 2003. Metal sulfide species in surface waters. www.mite-rn.org. Michalke, B. 2003. Element speciation defi nitions, analytical methodology, and some examples. Ecotox. Environ. Safety . 56, 122-139. Miller, W.P., Martens, D.C., Zelazny, L.W. 1986. Effect of seque nce in extraction of

trace metals from soils. Soil Sci. Soc. Am. J. 50, 598-601. Nelson, D.W., and Sommers, L.E. 1996. Organic Matter. In: Methods of Soil Analysis

Part 3. Soil Science Societ y of America. Madison, WI. 1004. Plumb, R.H., Jr. 1981. Procedures for handling and chemical analysis of sediment and water samples. Technical Report. EPA/CE-18-1. Schank, A. 2003. Mobility of arsenic in a sh allow aquifer at the Savannah River Site. Masters Thesis, Clemson University. Tessier, A., Campbell, P.G.C., and Bisson, M. 1979. Sequential extraction procedure for the speciation of particulate trace metals. Anal. Chem. 51(7): 844-851.

United States Environmental Protection Agency (USEPA). 1994. EPA Method 200.8,

Determination of trace elements in wa ter and wastes by inductively coupled plasma-mass spectrometry, Revision 5.4, Methods for the Determination of Metals in Environmental Samp les- Supplement 1, EPA/600/R-94-111.- 56- Scientific Final Report



### TASK 3

Introduction

For purposes of this research, simulated F GD wastewaters (based on projections from actual FGD wastewaters) were used as models for treatment of FGD wastewaters. These simulated FGD wastewaters were produced by amending municipal water with arsenic (As), mercury (Hg), selenium (Se), chloride (Cl - ) and sulfate (SO 4 2- ) salts. Three elements (As, Hg, and Se) were identified as targeted constituents for this treatment process due to their relatively high concentra tions in the actual FGD wastew aters, as well as background concentrations or pre-existing problems asso ciated with these elements at most power company sites. For this research, simula ted FGD wastewaters were treated using specially designed pilot-scale constructed wetland treatment systems. These systems consisted of a detention basin followed by three treatment trains with four wetland treatment cells in each train. Discharged wast ewater (i.e. outflow wastewater) from the full-scale treatment system has to meet wate r quality criteria set forth under the Clean Water Act and the National Pollution Discharg e Elimination System (NPDES). Along with aqueous concentration limits for selectiv e elements, discharged wastewater must not elicit significant toxicity to testing organisms.

The first objective of this research was to m easure changes in concentrations of targeted

constituents in simulated FGD wastewater before and after treatment by a constructed wetland treatment system (untreated inflow versus final outflow of treated FGD wastewater). These measurements helped to characterize the potenti al chemical exposure that organisms may encounter if exposed to th ese wastewaters. Another objective of this research was to evaluate the toxicity of aqueous simulated FGD wastewater to Ceriodaphnia dubia Richard and Pimephales promelas Rafinesque before and after treatment by the pilot-scale constructed we tland treatment system. These two organisms are commonly used in the United States for testing waters and wastewaters (U.S. EPA, 1984). C. dubia is a sentinel invertebrate species widely used for toxicity testing in NPDES programs (Spehar and Fiandt, 1986, Mount et al., 1997 Brix et al., 2001). P. promelas is a freshwater minnow that is also wide ly distributed in North America and is found in lentic systems. Responses of P. promelas to exposures of metals and organics

differ from those of C. dubia ; therefore both test species were used in this research in order to better understand any toxicity of the simulated FGD wastewater (Spehar and Fiandt, 1986, USEPA, 1987, Mount et al., 1997). Toxicity endpoints for C. dubia included mortality and reproduction and for P. promelas endpoints included mortality and growth.

An objective of this research also included toxicity assessment of the sediments within the pilot-scale constructed wetla nd treatment systems. Bulk se diment toxicity testing was conducted on previously exposed sediment ( hydrosoil) within the constructed wetland treatment systems for remediation of si mulated FGD wastewaters (Task 1). Two commonly used sediment dwelling organisms ( Hyalella azteca and Chironomus tentans ) were used to measure respons es of survival and growth after an exposure period of 10- 57- days to the treatment hydrosoil. To determ ine the toxicological significance of these results or responses, organisms exposed to sediments from the constructed wetland treatment system were compared to controls tested in reference sediment and moderate

hardness water.

MATERIALS AND METHODS

Simulated FGD wastewaters used for this research were mode led after actual FGD wastewater projections. Arse nic and mercury were amended using a single reagent salt for each element. Selenium, however, was formulated using two reagent salts (sodium selenite and sodium selenate) to simulate th e speciation of selenium found in actual FGD wastewater. All amendments and mixing of the simulated FGD wastewaters were conducted in the equalization basi n of the system. The specie s of each element used in this research, and the source compound used for amendment of the simulated FGD

wastewaters are listed in Table 11.

Sample Collection and Analysis

Water samples used for analysis (1000-ml) and toxicity testing (4-L) were collected in 1000-mL Nalgene  containers from the equalization basin and final outflow cell from the treatment system. Outflow samples were collected on a time course commensurate with hydraulic retention time (HRT). Of the 1000-mL water sample collected for analysis, a 10-mL aliquot was immediately pres erved in the laboratory with concentrated trace metal grade nitric acid to pH < 2 for metals analysis, while the remaining volume was retained in order to complete the re maining analyses such as chemical oxygen demand (COD), pH, alkalinity, hardness, conduc tivity, and toxicity te sting. Methods and detection limits for all analys es are listed in Table 12. In order to evaluate variance in concentrations of targeted constituents and its effect on toxicity in FGD wastewaters, two

simulated FGD wastewaters were treated usi ng the constructed wetland treatment system. These samples were collected during loading of the low-intermediate ionic strength FGD wastewater (treatment weeks 23 and 24), each with inflow (pre-tr eatment) and outflow (post-treatment). However, for clarity purpos es throughout the remainder of this report, treatment Week 23 and 24 will be denoted as Sample One and Two.

Table 11 . Elements and form used for amendments of simulated FGD wastewater.

Element Form Compound

Arsenic As(+III) 100% Sodium

arsenite

Mercury Hg(+II) 100% Mercuric

nitrate

Selenium Se(+IV)

33.333% Sodium

selenite

Selenium Se(+VI)

66.666% Sodium

selenate- 58- Table 12 . Analytical methods for parameters monitored for FGD wastewater.

Parameter Method Detection Limit

Temperature Direct Instrument ation: YSI Model 52 0.5°C

pH Direct Instrumenta tion: Orion Model 420A 0.01

Conductivity Direct Instrument ation: YSI 30 0.1 μS/cm

Alkalinity Standard Methods: 232 0 B 2 mg/L as CaCO3

Hardness Standard Methods: 2340 C 2 mg/L as CaCO3

DO 1 Direct Instrumentation: YSI Model 52 0.1 mg/L

COD 2 Closed reflux colorimetry (HACH - 3 mg/L modified from Standard Methods: 5220D)

NPOC 3 Shimadzu TOC-V CPH Total Organic 4 μg/L Carbon Analyzer

BOD 5 4 Standard Methods: 5210 B 0.1 mg/L

TSS 5 Standard Methods: 2540 D 0.1 mg/L

TDS 6 Standard Methods: 2540 C 0.1 mg/L

Selenium Inductively Coupled Plasma (ICP): EPA 200.7 0.0022 mg/L

Mercury Mercury Analyzer: EPA 245.1 0.0001 mg/L

Chloride HACH Colorimetric Method 8207 25 mg/L

Sulfate Standard Methods: 4500 E 1 mg/L

Arsenic ICP: EPA 200.7 0.0013 mg/L

1 Dissolved Oxygen

2 Chemical Oxygen Demand

3 Non-purgable Organic Carbon

4 Five-day Biological Oxygen Demand

5 Total Suspended Solids

6 Total Dissolved Solids

Constructed Wetland Treatment System

Specially designed pilot-scale wetland treatme nt systems were constructed at Clemson University in Clemson, SC. The system consisted of a 6,800-L upstream equalization basin followed by three parallel treatment trai ns. The equalization basin was incorporated into this treatment process to simulate full-scale design parameters, such as settling of particulates and equilibration of elements within the bulk aqueous phase. Each treatment- 59- train consisted of four stages in series (from upstream to downstream), including two wetland cells planted with Schoenoplectus californicus (C.A. Mey.) Pa lla (California bulrush), a gravel manganese oxidation basin, and a final wetland cell planted with Typha angustifolia Linneus (narrowleaf cattail). Each treatment cell consisted of a 378-L

Rubbermaid  utility tank. Overlying water depth and hydrosoil depths were 30 cm each in the wetland cells. Total hydraulic reten tion time (HRT) was four days (24 hours per treatment stage). Simulated FGD wastewater was mixed in the equalization basin and pumped to each treatment train at a constant flow rate (ml/min) using FMI  (Fluid Metering, Inc.) piston pumps (one pump per treatment train). Flow of FGD wastewater through the treatment system trains was su rface flow propagated by gravity, and cells were connected by PVC piping.

Toxicity Experiments

Aqueous Toxicity

Treatment efficiency of simulated FGD wa stewaters by pilot-scale constructed wetland treatment systems was accessed by m easuring toxicity endpoints for C. dubia and P. promelas . Toxicity endpoints for C. dubia included mortality and reproduction, and for P. promelas endpoints was mortality. These two organisms are commonly used in the United States for testing of waters and wastewaters (Lewis et al., 1994). C. dubia is a freshwater microcrustacean, widely distributed in temp erate waters throughout North

America. P. promelas is a freshwater minnow that is al so widely distributed in North

America and is found in lentic systems. For aqueous toxicity assessment, 7-d chronic toxicity experiments were conducted with bot h species using U.S. EPA methods (Lewis et al., 1994). Test treatments included an untr eated control, as well as inflow and final

outflow dilutions of simulated FGD wastewat er. Dilutions were made using moderate hardness laboratory water as defined by Lewis et al. (1994).

Bulk Sediment Toxicity

To further understand the chemical fate of As, Hg, and Se in constructed wetland treatment systems, evaluation of sediment toxicity was conducte d with previously exposed hydrosoil used in Task One of this report. Sediment dwelling organisms such as Hyalella azteca and Chironomus tentans can provide useful information on the bioavailability of toxic elements or mol ecules when exposed to non-contaminated or

contaminated sediment. H. azteca and C. tentans have been used in many toxicity experiments due to their interaction with fres hwater sediments and re lative sensitivity to contaminants in the sediments (EPA 2000). These experiments along with studies of elemental binding strength (Task Two) can be used to further assess the risk posed by

sediment used in treatment of simulate d FGD wastewater with constructed wetland treatment systems. For sediment toxicity as sessment, 10-d static toxicity experiments

were conducted with H. azteca and C. tentans following U.S. EPA methods (EPA Test Methods 100.1 and 100.2). Test treatments in cluded an untreated control and sediment samples from wetland cells 1, 2, and 4. Sediment toxicity experiments were not conducted with wetland cell 3, since sediment wa s not used in the construction of this cell (i.e. manganese-oxidation basin). Each expe rimental treatment included site-sediment- 60- volumes of 40 ml and 160 ml of moderately hard water and three replicates. Controls were tested in a reference sediment and moderately hard water at the same ratios listed above. Survival and growth were measured at th e conclusion of the te st (10-d). Statistical differences were evaluated using chi-square analysis and analysis of variance (ANOVA) with least-squared differences (LSD) as the mean separator. H. azteca were supplied food in the form of three 7 mm maple leaf di scs from initiation to conclusion of the experiments. C. tentans were feed 0.5 ml of ground tetramin daily.

RESULTS

Removal of Targeted Constituents for FG D Wastewater used in Toxicity Testing

In order to understand data fr om toxicity experiments and further characterize simulated FGD wastewaters, analyses of parameters such as COD, pH, alkalinity, hardness, conductivity, and solids were measured. Thes e data for Sample One and Sample Two

simulated FGD wastewaters are in Table 12. Re sults of the first objec tive, to measure the removal of the targeted consti tuents (As, Hg, Se) from the inflow to the outflow by the constructed wetland treatment system , are included in Table 13.

These data listed in Table 13 indicate that concentrations of ar senic, mercury, and

selenium decreased from the inflow to fina l outflow of the treatment system, with the exception of arsenic in sample 2, in which the aqueous concentra tion increased from 0.071 mg/L to 0.16 mg/L. In this situation, it is assumed that possible particulate contamination occurred in the metal analysis aliquot. Another constituent of concern and potential source of toxicity, in the simu lated FGD wastewater is chlorides. The

concentration of chlorides decreased from in flow to outflow of treatment system for Sample One simulated FGD wastewater. However, in Sample Two simulated FGD wastewater, the concentrati on of chlorides increased fr om 5250 mg/L to 5416 mg/L.

Table 13 . Water quality parameters of simulated FGD wastewater from inflow to final outflow of the pilot-scale constr ucted wetland treatment systems.

Parameter Sample 1 Inflow Sample 1 Outflow Sample 2 Inflow Sample 2 Outflow

Temp °C 19.93 19.88 20.13 19.69 DO mg/L 8.59 8.75 8.37 8.69
pH 6.68 6.73 6.55 6.9 Alk mg/L 58 74 68 82 Hard mg/L 12800 9400 12400 11700

Cond mS 9.43 9.91 12.88 13.87 BOD mg/L 11.03 3.1 9.92 3.25
COD mg/L 241 182 236 186 TSS mg/L 65.05 83.87 67.75 121.8
TDS mg/L 12536 12753 11998 11826 NPOC mg/L 228.52 33.04 93.98 42.67

As mg/L 0.073 0.028 0.071 0.17 Se mg/L 1.8 0.19 1.8 0.52- 61- Hg mg/L 0.16 0.005 0.16 0.00733

Cl

- mg/L 4150 3800 5250 5416

SO 4 mg/L 407 478 457 625

Aqueous Toxicity Experiments

Survival (Inflow to Final Outflow)

To compare differences in survival from th e inflow to final outflow of the treatment system using C. dubia and P. promelas, two by two contingency ta bles (chi squared) comparing survival probabilities of inflow vs. outflow dilutions of the simulated FGD

wastewater were used. Differences were eval uated using Fisher’s exact test (two sided probability p =0.05).

Survival data for Sample One FGD wast ewater (Figure 21) indicate that for C. dubia there was a significant decrease in toxicity from inflow to final outflow of the system for the dilutions of 3.125%, 6.25%, 12.5%, and 25% wa stewater. Survival data for Sample Two (Figure 22) indicate that for C. dubia there was a significant decrease in toxicity

from inflow to final outflow for the dilu tions of 6.25%, 12.5%, and 25% wastewater. For P. promelas survival data for the Sample One FGD wastewater (Figure 23) indicate that

none of the dilutions of wastewater were st atistically different fr om inflow to final outflow. Survival data for Sample Two (Figure 24) show that for P. promelas there was a significant decrease in toxicity for the dilutions of 6.25% and 12.5% wastewater.

C. dubia reproductive data (treatments; i.e. di lutions) were evaluated in comparison to control organisms using a one-way an alysis of variance test (ANOVA; α =0.05) and mean separation using a least significant differe nce test (LSD). For Sample One FGD wastewater (Figure 25), there was a significant increase in reproduction from the inflow to the outflow of the treatment system for the dilutions of 0.78%, 1.56%, 3.125%, and 6.25% wastewater. For Sample 2 FGD wast ewater (Fig 2.6) there was a significant increase in reproduction for the dilutions of 3.125%, 6.25%, and 12.5% wastewater.

An additional objective of these toxicity experiments was to compare and contrast differences in responses of C. dubia and P. promelas to simulated FGD wastewaters. To compare differences in survival of C. dubia and P. promelas, a two-by-two contingency table (chi-squared) was us ed to compare the survival probabilities of C. dubia vs. P. promelas exposed to varying dilutions of simula ted FGD wastewaters. Differences were further evaluated using Fisher’s exact test (two sided probability p =0.05). For Sample One simulated FGD wastewater (Figure 27), there was a significant difference between the responses, in terms of mortality, of C. dubia and P. promelas to wastewater dilutions of 3.125%, 6.25%, 12.5%, and 25%. The obse rved potency (respo nse in organism mortality to a change in percentage d ilution of wastewater) of Sample One for C. dubia

was 21.32 and 1.2 for P. promelas. For Sample Two (Fig 28) the responses of C. dubia

and P. promelas were significantly different only at a wastewater dilution of 6.25%. The observed potency of Sample Two for C. dubia was 4.11 and 7.2 for P. promelas.- 62- 0 20 40 60 80 100

C t

r 0

. 3

9 0

. 7

8
1 . 5

6

3

. 1

2

5 6

. 2

5
1 2

.

5 2 5 5 0 1 0

0

Simulated FGD Wastewater (%)Survival (%) Pre-treatment Post-treatment

Figure 21 . Response, in terms of survival, of C. dubia to the inflow and the outflow from the treatment system for Sample One simula ted FGD wastewater (T rains A, B, and C combined). Concentrations of 0.39% post-tr eatment and 50% pre-treatment were not

tested.



### 0 10 20 30 40 50 60 70 80 90 100

Ctr 0 .39 0

. 7

8 1.56 3.125 6.25 12

. 5 25 50 1 0

0



### Simulated FGD Wastewater (%)Survival (%) Pre-treatment Post-treatment

Figure 22 . Response, in terms of survival, of C. dubia to the inflow and the outflow from the treatment system for Sample Two simula ted FGD wastewater (Trains A, B, and C combined). Concentrations of 0.39% post-tr eatment and 50% pre-treatment were not

tested.- 63- 

### 0 20 40 60 80 100

Ctr 0. 3

9 0

. 78 1. 5

6

3 .12 5 6. 2

5
1 2

.

5 25 5 0 100



### Simulated FGD Wastewater (%)Survival (%) Pre-treatment Post-treatment

Figure 23 . Response, in terms of survival, of P. promelas to the inflow and the outflow from the treatment system for Sample One simulated FGD wastewater (Trains A, B, and C combined). Concentrations of 0.39% post- treatment and 50% pre-treatment were not

tested.



### 0 20 40 60 80 100

Ctr 6.25 12.5 25 37.5 50 62.5 75 100

Simulated FGD Wastewater (%)Survival (%) 

### Pre-treatment Post-treatment

Figure 24 . Response, in terms of survival, of P. promelas to the inflow and the outflow from the treatment system for Sample Two si mulated FGD wastewater (Trains A, B, and C combined).- 64- 0 5 10 15 20 25

Ctr 0.39 0.78 1.56

3

. 1 25 6.25 12.5 2 5 5 0 100

Simulated FGD Wastewater (%)Reproduction (MeanNeonates/Female) Pre-treatment Post-treatment

Figure 25 . Response, in terms of reproduction, of C. dubia to the inflow and the outflow from the treatment system for Sample One simulated FGD wastewater (Trains A, B, and C combined). Concentrations of 0.39% post- treatment and 50% pre-treatment were not

tested.

0 5 10 15 20 25

C t r 0

. 3

9 0

. 7

8

1 . 5

6

3

. 1 2

5 6

. 2

5

1 2

.

5 2 5 5 0 1 0

0

Simulated FGD Wastewater (%)Reproduction (MeanNeonates/female) Pre-treatment Post-treatment

Figure 26 . Response, in terms of reproduction, of C. dubia to the inflow and the outflow from the treatment system for Sample Two si mulated FGD wastewater (Trains A, B, and C combined). Concentrations of 0.39% post- treatment and 50% pre-treatment were not

tested.- 65- Another component of this research was to measure changes in responses of C. dubia and P. promelas to two temporally separated sample s of simulated FGD wastewater each possessing different concentrations of constituen ts. To compare differences in survival of

C. dubia and P. promelas, a two by two contingency table (chi squared) was used to compare survival probabilities of Sample One vs. Sample Two simulated FGD

wastewater dilutions. Differences were conf irmed using Fisher’s exact test (two sided probability p =0.05) due to the samp le sizes tested (n < 10).

When comparing C. dubia survival between Sample One and Two FGD wastewaters (Figure 29), only the dilutions of 3.125% were statistically different from each other. When comparing P. promelas survival between Sample One and Two FGD wastewaters (Figure 30), only the dilutions of 25% were statistically different, and the dilutions of 12.5% were close to being statistically diffe rent with a p value of 0.0573. Simulated FGD

wastewaters used in this research were dilu ted as low as 0.39%, in order to find the no

observable effect concentration (NOEC) defined in this research as the concentration at which reproduction and mortality were not affected (dilutions not statistically different in comparison to control organisms for the desired test parameter). Toxi city observed in the tested dilutions (both samples) was not solely due to the targeted constituents of concern (As, Hg, and Se), but primarily dependent on the chloride concentrations. This statement

should be reconsidered when chloride c oncentrations are diluted and do not cause significant effects on mort ality or reproduction. The NOEC for a chloride-only experiment was 640mg/L as Cl - (7-day static/renewal toxicity test). With these data, it is a fair assumption that toxicity observed at or below 640 mg/L of chlorides is due to multiple elements within the matrix tested. Th erefore, the pilot-scale constructed wetland treatment systems can be classified as performing optimally when NPDES limits and toxicity tests are met, but only after dilutions or co-man agement other mixing waters,

since chlorides are residual ions in solution that cannot be removed using this treatment

system.

The constructed wetland treatment systems used in this research were not designed to remove chlorides from the wastewater; and nearly 100% of chlorides input into the system remain in solution after discharge from the final wetland cell (variation in concentrations occur, i.e. evaporation and precipitation of water). Concentrations of

chlorides in the undiluted pre-treatment FGD wastewaters and the undiluted posttreatment samples exceeded the known 48-hr LC 50 values reported in literature for C.

dubia and P promelas using MgCl 2 and CaCl 2 . Calcium chloride and magnesium chloride are the predominant chlorides f ound in the FGD wastewater. The 48-hr LC 50 values of C. dubia for these two salts re ported in literature are 0.88 and 1.83 g/L respectively, and 96-hr LC 50 s were 2.12 and 4.63 g/L respectively for P. promelas (Mount et al., 1997). Sample One simulated FGD wastewater had chloride concentrations in the pre-treatment and pos t-treatment that ranged from 3475 mg/L to 4150 mg/L. For Sample Two simulated FGD wast ewater, chloride concentrations ranged from 5075 mg/L to 5650 mg/L throughout the test duration from inflow to final outflow.- 66- 0 20 40 60 80 100

Ctr 0. 3

9 0.78

1 . 56

3

. 1 2

5 6.25 12

. 5 2 5 100

Simulated FGD Wastewater (%)Survival (%) C.d. P.p.

Figure 27 . Comparative responses, in terms of survival, of C. dubia and P. promelas to simulated FGD wastewater Sample One.



### 0 20 40 60 80 100

Ct r 0

. 39 0.7 8

1 . 56

3

.1

2

5 6.25

1 2.

5 25 3 7

.5 50 62.5 75 100



### Simulated FGD Wastewater (%)Survival (%) 

### C.d. P.p.

Figure 28 . Comparative responses, in terms of survival, of C. dubia and P. promelas to simulated FGD wastewater Sample Two. C oncentrations of 0.39%, 0.78%, 1.56%, and

3.125% for P. promelas and 37.5%, 50%, 62.5%, and 75% for C. dubia were not tested.- 67- Figure 29 . Comparative responses, in terms of survival, of C. dubia to simulated FGD wastewater Samples One and Two.



### 0 20 40 60 80 100

Ctr 0. 3

9 0.78

1 .5

6

3.125 6.25 12.5 2 5 37

. 5 50 62. 5 75 1 0

0



### Simulated FGD Wastewater (%)Survival (%) Sample 1 Sample 2

Figure 30 . Comparative responses, in terms of survival, of P. promelas to simulated FGD wastewater Samples One and Two. Concentrations of 0.39%, 0.78%, 1.56%, and 3.125% for Sample Two (Sample One) and 37.5%, 50%, 62.5%, and 75% for Sample One (sample Two) were not tested. 0 20 40 60 80 100

Ctr 0.39 0.78 1.56 3.125 6.25 12.5 25 100

Simulated FGD Wastewater (%) Survival (%) Sample 1 Sample 2- 68- Bulk Sediment Toxicity

To determine the bioavailability of inorganics (i.e. As, Hg, and Se) in the hydrosoil of the constructed wetland treatment system, two se ntinel toxicity testing organisms were exposed to sediment samples from each wetland cell. Testing organisms were chosen due to previous research on sediment toxicity characterization and a ppropriate EPA methods (Lewis et al. 1994; EPA Methods 100.1 and 100.2).

Hyalella azteca

In review of results, no observable toxicity effects (survival or growth) were measured for sediment samples collected from wetland cells 1, 2, and 4. Complete survival (100%) was observed in all treatment and control repl icates. Average weight per organism was 0.00023 g for controls, 0.0006 g for wetla nd cell 1, 0.0093 g for wetland cell 2, and 0.00062 g for wetland cell 4. Final weights per or ganism were greater for treatments in comparison to control (Table 13). From thes e results, there is statistical evidence to conclude that survival and growth of H. azteca are impaired by exposure to sediments/hydrosoil from constructed wetland treatment systems used in the remediation

of simulated FGD wastewater.

Table 14. Sediment toxicity results in terms of survival and growth measurements of Hyalella azteca for wetland treatments and controls.

Average

Percent Total Weight per Average Treatment Rep Survival Survival H.a. Wt(g) Org. (g) Wt/Org (g)

1 10/10 0.00237 0.00024

Control 2 10/10 100% 0.00231 0.00023 0.00023

3 10/10 0.00211 0.00021

1 10/10 0.00339 0.00003

1st Wetland Cell 2 10/10 100% 0.00975 0.00010 0.00060

3 10/10 0.00488 0.00005

1 10/10 0.00296 0.00003

2nd Wetland Cell 2 10/10 100% 0.0109 0.00011 0.00093

3 10/10 0.01409 0.00014

1 10/10 0.00841 0.00008

4th Wetland Cell 2 10/10 100% 0.00297 0.00003 0.00062

3 10/10 0.00711 0.00007

Chironomus tentans

In review of results, control organisms aver aged 90% survival, while the first treatment cell averaged 80% survival. Both treatme nt cells 2 and 4 averaged 96.7% survival. Average weight per organism was observ ed as 0.00089 g for controls, 0.00133 g for wetland cell 1, 0.0117 g for wetland cell 2, and 0.00138 g for wetland cell 4. The average weight per organism was greater in the three sediment treatments compared to the control (Table 14). From these results, ther e is no statistical evidence to conclude that growth of C. tentans is impaired by exposure to sedime nts/hydrosoil from constructed wetland treatment systems used in the remediation of simulated FGD wastewater.- 69- Table 15. Sediment toxicity results in terms of survival and growth measurements of

Chironomus tentans for wetland treatments and controls.

Average Percent Total Weight per Average Treatment Rep Survival Survival C.t. Wt (g) Org. (g) Wt/Org (g)

1 9/10 0.00976 0.00108

Control 2 8/10 90% 0.00580 0.00073 0.00089

3 10/10 0.00872 0.00087

1 10/10 0.00957 0.00096

1st Wetland Cell 2 6/10 80% 0.01028 0.00171 0.00133

3 8/10 0.01049 0.00131

1 10/10 0.01152 0.00115

2nd Wetland Cell 2 9/10 96.7% 0.00962 0.00107 0.00117

3 10/10 0.01300 0.00130

1 10/10 0.01386 0.00139

4th Wetland Cell 2 9/10 96.7% 0.01447 0.00161 0.00138

3 11/11 0.01272 0.00116

DISCUSSION

In the constructed wetland treatment systems, the targeted constituents (As, Hg, and Se) decreased from the inflow of the system to the outflow of the system for both samples of simulated FGD wastewater. Due to complete mortality of both C. dubia and P. promelas in both samples of simulated FGD wastewater, dilutions of these samples were used for toxicity experiments. Dilutions allowed for determination of upper and lower thresholds of toxicity. In the dilutions of simulated F GD wastewater used for toxicity experiments both the acute and reproductive toxicity to C. dubia decreased from the inflow to final outflow of this treatment system. The pilot-scale wetland treatment system also decreased the acute toxicity to P. promelas in dilutions of simulated FGD wastewater from inflow to final outflow samples. Understanding that chloride concentrati ons through the system remain relatively unaffected, it can be hypothesize d that decreases in toxicity for dilution experiments between inflow and outflow sample s can be correlated with removal of toxic soluble elements (arsenic, mercury, and selenium) by this treatment system.

Aqueous Toxicity Experiments

Observed responses of the two species were di fferent as literature suggests (Spehar and Fiandt, 1986, USEPA, 1987, Mount et al., 1997), and the observed differences in species sensitivity may be attributed to chloride , as the two species respond at different

concentrations of the two main form s of chloride present. As CaCl 2 , chloride has a 48-hr

LC 50 of 1.83 g/L for C. dubia and a 96-hr LC 50 4.63 g/L for P. promelas. Chloride as MgCl 2 has a 48-hr LC 50 of 0.88 g/L for C. dubia and a 96-hr LC 50 of 2.12 g/L for P. promelas (Mount et al., 1997)

When comparing C. dubia survival between treatment weeks (Figure 29) only the

dilutions of 3.125% were statistic ally different from each other, in which greater survival was observed for Sample One. When comparing P. promelas survival only, the dilutions- 70- of 25% were statistically different (Figure 30), and the dilutions of 12.5% were close to being statistically different with a p-valu e of 0.0573. For Sample One, the concentration of chlorides was approximately 4150 mg/L wh ile in Sample Two, th e concentration of chlorides was approximately 5250 mg/L.

Bulk Sediment Toxicity Experiments

Hyalella azteca

Toxicity endpoints of survival and growth for H. azteca did not differ significantly between sediment treatments (exposed sedi ment from wetland cells 1, 2, and 4) and control organisms. No mortality occurred dur ing the experimental duration of 10-d and organism weights were greater for treatment sediments in comp arison to controls. In this situation, it is plausible to hypot hesize that non-toxic food sour ces (i.e. detritus) were in greater abundance than was availa ble in the control sediment.

Chironomus tentans

Toxicity endpoints of survival and growth for C. tentans did not differ significantly between sediment treatments (exposed sedime nt from wetland cells 1, 2, and 4) and control organisms. Minimal mortality occurr ed during the experime ntal duration of 10-d and midge weights were greater for treatment se diments in comparison to controls. In this situation, it is plausible to hypothesize that non-toxic food sour ces (i.e. detritus) were in greater abundance than in the control sediment. Average survival was observed as 90% for controls, 80% for wetland cell 1, and 96.7% for wetland cells 2 and 4.

CONCLUSIONS

For efficient implementation of FGD scrubber un its at fossil-fuel fi red power plants, an

effective and reliable wastewater treatment system is required. Large volumes of FGD wastewater will be produced from scrubbe r systems within smoke stacks, and this variable aqueous matrix must be treated to eliminate contaminants in order to achieve discharge limitations establ ished under the National Pollution Discharge Elimination System (NPDES) and Clean Water Act. Sp ecifically designed constructed wetland treatment systems have been used to treat each of these elements independently, (Hansen
et al., 1998; Kaplan, et al., 2002; Thompson, et al., 2003) but this concept or technology had not been “proven” for FGD wastewater s. Wetlands possess un ique reactions not occurring in other aquatic or terrestrial sy stems (Jacob and Otte, 2002). This pilot study was conducted in order to develop confidence in the ability of a constructed wetland treatment system to treat FGD wastewater.

While the undiluted outflow from this constr ucted wetland treatment system was toxic in terms of reproduction to C. dubia at dilutions as low as 0.78%, th is toxicity is likely due

to the elevated concentra tion of chlorides (in excess of 4000 mg/L) and not the constituents which were targeted for removal by this treatment system. Based on- 71- inorganic analysis of pre- and post-treatment wastewater from the pilot-scale constructed wetland treatment system, aqueous constituen ts of concern (As, Hg, and Se) were significantly decreased as well as or ganism responses of toxicity for C. dubia and P. promelas

. Bulk sediment toxicity, in terms of survival and reproduction, were not observed with exposed hydrosoil from any wetland cell treatments and is consistent with the sequential extraction data from Task Tw o. Bioavailability of these elements should correlate to estimate binding strengths (sequential extractions). Under this assumption, responses of H. azteca and C. tentans indicate that As, Hg, and Se are transferred into

non-bioavailable forms within the sediment and should not pose a ri sk unless disturbed. Overall, pilot-scale constructed wetla nd treatment systems decreased aqueous concentrations of toxic inorga nics and toxic responses of C. dubia and P. promelas with co-management of dilution water. These system s can provide scaling coefficients for fullscale design, in which actual FGD wastewater can be treated to meet NPDES restrictions of discharge wastewater.

OVERALL CONCLUSIONS

Observations from this research indicate that constructed wetland treatment systems specially designed for FGD wastewater are bo th practical and effi cient in removal of soluble elements of concern (As, Hg, and Se).

Future research should include continued mon itoring of these systems with simulated and

actual FGD wastewaters for a mo re comprehensive understanding of temporal variations

in removal rates and extents of these elem ents. Also, research should focus on minor manipulations of these systems for greater re moval of all elements including changes in HRTs, organic matter and composition, specia tion of iron within selected cells, and

sulfide concentrations. These data allow a first-order assessment of the chemical properties of these precipitated elements within the sediment.

In conclusion, constructed wetland treatment systems can be utilized for many FGD wastewaters. These systems have many adva ntages in comparison to other treatment processes including: pub lic perception (“green” chemistr y), low maintenance and simple monitoring processes, efficiency in remova l rates and extents of elements commonly observed in FGD wastewater, minimal cap ital and operating costs, and spatial requirements.- 72- REFERENCES

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